Hi bobojo,
Your code contains a very minor error which is easy to correct in one of two manners. It appears that you forgot to add: int collisions; to your typedef struct, as shown below.
typedef struct {
int x;
int y;
int width;
int height;
int collisions;
const unsigned int *bitmap;
} ts_sprite;
ts_sprite ball = {44,28,4,4,0,ballBitmap};
If you don't wish to utilize the collision tracking variable, you could also leave your typedef struct as is and delete the 0 value as shown below:
ts_sprite ball = {44,28,4,4,0,ballBitmap};
Whichever method you choose, the important thing is to keep both consistent to each other.