|Not sure exactly what it is your doing, but try this:|
After using one of your screen capture utilities to get the picture.
It saves it as .bmp file. Correct?
You need to convert the .bmp to .jpg
MS Paint should allow you to do this.
Select All Programs,
Double Click Paint
Navigate to where you saved your .bmp file
Double Click the .bmp file.
After the .bmp files opens,
Select Save As,
Change the Save As Type from .bmp to .jpg
This should convert your .bmp to .jpg