Problem with jumping

[link5019]

I am working on a platformer using C++ and Allegro 5. So far the camera works, as well as drawing things. The jumping however does not work. The player will go up but won't go down, but if he does, he goes through the ground even though the collision should be working. If anyone could help, please, that would be great! :)

//object header
#include "objects.h"

//Allegro headers
#include <allegro5\allegro.h>
#include <allegro5\allegro_primitives.h>
#include <allegro5\allegro_font.h>
#include <allegro5\allegro_ttf.h>
#include <allegro5\allegro_image.h>

//Globals===============================

//screen variables
int screenWidth = 640;
int screenHeight = 480;
int worldWidth = 3392;
int worldHeight = 960;
float camX = 0;
int camY = 0;
bool can_jump = true;
bool in_air = false;
int plyr_vel = 2;
int hang_time;

//player controls
enum KEYS {LEFT, RIGHT, DOWN, SPACE, P};
bool keys[5] = {false, false, false, false, false};
bool camAct = true;

//prototypes

//player
void InitPlayer(Player &plyr);
void DrawPlayer(Player &plyr);
void MoveLeft(Player &plyr);
void MoveRight(Player &plyr);
void MoveDown(Player &plyr);
void Jump(Player &plyr);

void InitGround(Ground &ground, Player &plyr, int x, int y);
void DrawGround(Ground &ground, Player &plyr, int x, int y);
void CollideGround(Ground &ground, Player &plyr, int x, int y);
//Camera
void cam(Player &plyr);


//main
int main(void)
{
	//primitive variables
	const int FPS = 60;
	bool done = false;
	bool redraw = true;
	bool isGameOver = false;
	int x = 0;
	int y = 0;

	int imageWidth = 0;
	int imageHeight = 0;

	//object variables
	Player plyr;
	Ground ground;

	//Allegro variables
	ALLEGRO_DISPLAY *display = NULL;
	ALLEGRO_EVENT_QUEUE *event_queue = NULL;
	ALLEGRO_TIMER *timer = NULL;
	ALLEGRO_FONT *font18 = NULL;
	ALLEGRO_BITMAP *bitmap = NULL;

	//Initialization Functions

	//initialize Allegro
	if(!al_init())										
		return -1;

	//create our display object
	display = al_create_display(screenWidth, screenHeight);			
	//test display object
	if(!display)										
		return -1;

    //Allegro Module Init
	al_init_primitives_addon();
	al_install_keyboard();
	al_init_font_addon();
	al_init_ttf_addon();

	al_init_image_addon();

	bitmap = al_load_bitmap("world1-1.png");

	//event creation
	event_queue = al_create_event_queue();
	timer = al_create_timer(1.0 / FPS);

	//init random generator
	srand(time(NULL)); 

	//Game initilization

	//player
	InitPlayer(plyr);
	 InitGround(ground, plyr, 0, 0 );

	//Font (TBA)
	//--------------------------------

	//Keyboard and other things initilization
	al_register_event_source(event_queue, al_get_keyboard_event_source()); 
	al_register_event_source(event_queue, al_get_display_event_source(display));
    al_register_event_source(event_queue, al_get_timer_event_source(timer)); 

	
	//timer start
	al_start_timer(timer);

	//game loop
	while (!done)
	{
		//event loader
		ALLEGRO_EVENT ev;
		al_wait_for_event(event_queue, &ev);//wait for an event.
		


		//events for key strokes
		if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
		{
			done = true;
		} 
		else 
			if (ev.type == ALLEGRO_EVENT_TIMER)
		{
			redraw = true;

			//keys for player
			if (keys[LEFT])
				MoveLeft(plyr);
			if(keys[RIGHT])
				MoveRight(plyr);
			if(keys[DOWN])
				MoveDown(plyr);
			if(keys[SPACE])
				Jump(plyr);
			if(keys[P]);


			//is game over checks
			if(plyr.lives <= 0)
			{
				isGameOver = true;
			}
		}
			//Is a key pressed
			else if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
			{
				switch (ev.keyboard.keycode)
				{
					//close key
				case ALLEGRO_KEY_ESCAPE:
					done = true;
					break;
					//Left arrow key
				case ALLEGRO_KEY_LEFT:
					keys[LEFT] = true;
					break;
					//Right arrow key
				case ALLEGRO_KEY_RIGHT:
					keys[RIGHT] = true;
					break;
					//Down arrow key
				case ALLEGRO_KEY_DOWN:
					keys[DOWN] = true;
					break;
					//Space bar
				case ALLEGRO_KEY_SPACE:
					keys[SPACE] = true;
					Jump(plyr);
					break;
				}
			}
			//Is a key released
			else if (ev.type == ALLEGRO_EVENT_KEY_UP)
			{
				switch (ev.keyboard.keycode)
				{
					//Left arrow key
				case ALLEGRO_KEY_LEFT:
					keys[LEFT] = false;
					break;
					//Right arrow key
				case ALLEGRO_KEY_RIGHT:
					keys[RIGHT] = false;
					break;
					//Down arrow key
				case ALLEGRO_KEY_DOWN:
					keys[DOWN] = false;
					break;
					//Space bar
				case ALLEGRO_KEY_SPACE:
					keys[SPACE] = false;
					Jump(plyr);
					break;
				}
			}

			
			if (hang_time > 0)
			{
				plyr.y -= plyr_vel;
				hang_time --;
			} else
				if (hang_time <= 0)
				{ 
					if (plyr.x < ground.boundX - 32 && plyr.y < ground.boundY - 32)
					{
					plyr.y += plyr_vel;
					}
					hang_time = 0;
					
			}


			//draw functions
			if (redraw && al_event_queue_is_empty(event_queue))
			{
				redraw = false;

				if (!isGameOver)
				{
					DrawPlayer(plyr);
					cam(plyr);

					for (int i = 0; i <= 1024; i += 16)
					{
						DrawGround(ground, plyr,i, screenHeight - 16);
						
					}
						
					

					al_draw_bitmap(bitmap, worldWidth / 2 - imageWidth , worldHeight / 2 - imageHeight , 0);
					al_draw_tinted_bitmap(bitmap, al_map_rgba(255,255,255,.5),x - camX,y -camY,0);
					
					
					
					//draw more things later
				}
				//add game over screen here.

				//display flipping
				al_flip_display();
				al_clear_to_color(al_map_rgb(0,0,0));
				
			}
			
		}//end while loop

		//Destroy all objects running program
		al_destroy_event_queue(event_queue);
		al_destroy_timer(timer);
		al_destroy_display(display);
		al_destroy_font(font18);

		return 0;

} //end main


//functions for game

//player
void InitPlayer(Player &plyr)
{
	plyr.x = 20;
	plyr.y = worldHeight / 2;
	plyr.IDS = PLAYER;
	plyr.lives = 3;
	plyr.speed = 4;
	plyr.boundX = 6;
	plyr.boundY = 7;
	plyr.score = 0;

	
}

void DrawPlayer(Player &plyr)
{
	al_draw_filled_rectangle(plyr.x - camX, plyr.y-32, plyr.x+10 - camX , plyr.y -48, al_map_rgb(0,255,0));
	
	

	if(plyr.x <= camX)
		plyr.x = camX;
	if (plyr.x >= screenWidth + camX - 10)
		plyr.x = camX + screenWidth - 11;

}

void MoveLeft(Player &plyr)
{
	plyr.x -= plyr.speed;
	if(plyr.x < 0) 
		plyr.x = 0;
		if(plyr.x <= camX)
		plyr.x = camX;
	


}

void MoveRight(Player &plyr)
{
	plyr.x += plyr.speed;
	if (plyr.x > worldWidth)
		plyr.x = worldWidth;
	if (plyr.x >= screenWidth + camX - 10)
		plyr.x = camX + screenWidth - 11;

	
	
}

void MoveDown(Player &plyr)
{
	//add code
}

void Jump(Player &plyr)
{
	if (can_jump == true && in_air == false)
	{
	in_air = true;
	can_jump = false;
	hang_time = 10;
	}
}

//camera

void cam(Player &plyr)
{
	
	// making sure the camera stays within the boundary of the game world
	if (camX < 0) camX = 0;
if (camY < 0) camY = 0;
if (camX > worldWidth - screenWidth) camX = worldWidth - screenWidth;
if (camY > worldHeight - screenHeight) camY = worldHeight - screenHeight;


// make the camera follow the player
if ( plyr.x > camX + screenWidth / 2 )
	camX += plyr.speed;
else 
	if (plyr.x < camX + screenWidth/2)
		camX -= plyr.speed;
	


}

void InitGround(Ground &ground, Player &plyr, int x, int y)
{
	ground.x = x;
	ground.y = y;
	ground.boundX = 48;
	ground.boundY = 48;
}
void DrawGround(Ground &ground, Player &plyr, int x, int y)
{
	al_draw_filled_rectangle(x - camX, y + 16, x + 16 - camX, y - 16, al_map_rgb(255,0,255));
}
void CollideGround(Ground &ground, Player &plyr, int x, int y)
{
	if (plyr.x < ground.boundX - 32 && plyr.y < ground.boundY - 32)
					{

				can_jump = true;
				in_air = false;
				plyr.y = ground.boundY - 32;

				if (plyr.y < ground.boundY - 32)
					plyr.y = ground.boundY-32;
}


}

[link5019]

Anybody?