Expression Design will sometimes...very annoyingly refuse to export slices or even whole images at the dimensions you specify.
The interesting part is...I can replicate this problem with a line (even if the lines boundaries are *exactly* at pixel boundaries), but if I have a rectangle that's positioned at exact pixel boundaries, the problem goes away.
The fix is:
- Turn of anti-aliasing
- If you can, use rectangles instead of lines
- Move vector shapes away from the edges of your image/slice
If you have lines right at the edge of your image and you have anti-aliasing turned on -- Expression Design decides that anti-aliasing is more important than your dimensions....surely you don't want to waste all that anti-aliasing data outside the edges :-) *sigh*