Leonid,
I don't really know what the game is supposed to do or how it is supposed to play. That's why I need you to tell me what problems to look for. There's no way to tell if it's improper coding or actual problems with the sprites and collision.
Here's something to note about sprite collision in DBC:
Collision is detected when the color channel in the pixel of one sprite overlaps the same color channel in another sprite. if there is no overlap, then there will be no collision detection.
For example, let's say a pixel on a sprite was colored red rgb(255,0,0) and the other sprites pixel color was blue rgb(0,0,255). Let's line them up so we can see if any of the channels match:
255,0,0
0,0,255
No they don't match so even if all of the pixels in one sprite were red, and all of the pixels in the other sprite were blue, there would be no collision detection because none of the channels overlap with a value other than 0.
Now what if one sprite were purple and the other blue:
rgb(255,0,255)
rgb(0,0,255)
You have over lap in the blue channel so therefore there would be collision detection.
IIn order for two sprites to collide, there have to be pixels that overlap in the same channel with values other than zero.
An idea might be to draw an outline around each of your sprites with a dark gray:
rgb(16,16,16)
That way, you'll always have some overlap except if the pixel is absolute black:
rgb(0,0,0)
Enjoy your day.