It could be something has come adrift whilst fitting one of those.
I once bought an Escort on which the dash lights didn't work, the guy reckoned it needed a fuse but as all 4 sidelights worked I knew it wasn't that simple.
I later found that the sidelights had been patched right to left because the fuse for the Rh sidelights and dash lights had blown. Someone (I'll not say who) was too thick to realise there were 2 fuses for the sidelights.
So nothing would suprise me TBH ;)