that's your problem...your layer may be affecting...is it set to "Pass Through"
also your document properties may be set differently than the image and changing the image as you bring them in
If you have the Mode set to CMYK or RGB and bring in an Indexed or other format it is possible to see alterations from the original.
Another note....twstats maps save very little information
take a full world...it's 2bits a pixel...pretty much red or green....which when loaded into an improperly configured document will show you only a red square...I've seen it happen.
The more zoomed in you are into a twstats map the more information per pixel...This is information above your head but i mention to get you on the right track.
Always save the raw image to disk. Open that original image and check what mode it is.
don't open as new layer try open the images seperately and then 'drag' it onto the other map you have opened and see what happens..
"Pass through" will show effects from another layer and mess with the colors
