png image problem, very newbie question

I've got a png image with its background color set to RGB 0, 0, 0. When I try to use the image the images background keeps showing through, why? Below is my Draw method, any help would be greatly appreciated.

Thanks

' draw the city
Method Draw()
SetBlend MASKBLEND
SetAlpha 1
SetScale .4, .4
SetRotation 0
DrawImage city, x, y
End Method

Can't seem to find it now, but I seem to remember that 0,0,0 is the default mask color...

try setting a mask of 0,255,0 or some other color that you are unlikely to have used in your images?

There should be nothing wrong with what you have done in this part of the program. You have set a few options so it might be a case of not setting them back afterwards (or somewhere else in the program).
Try creating a simple program to see whether you have it working with this image...
e.g.

Graphics 800,600
back = LoadImage("background.png")
fore = LoadImage("fore.png")
While Not KeyHit(key_escape)
   Cls
      DrawImage back,0,0
      SetBlend MASKBLEND 
      SetAlpha 1 
      SetRotation 0 
      DrawImage fore,100,100
flip
Wend  

umm,.... MASKBLEND lets the background show through, that's what it's for. If you want to show the black pixels use SOLIDBLEND.

I found out the problem, I had selected CMYK in photoshop. I changed it to RGB and it worked as it should. Thanks for everyones input.