When i feed it

Moths are just full of that dusty stuff in my experience. Try flies and spiders. If your VFT is new it could be in shock. If it's come out of dormancy recently it can sometimes be tricky to feed them.
try feeding it small crickets, doesn't seem to have any effect on the trap but the VFT definetly looks better for it. The flys round here make the trap die out.

Just rememebr that you do not have to feed a VFT.