Windows Movie Maker videos into movie maker they don’t work, when I hit play the screen is just black?

I am trying to use windows movie maker on windows 10 to create a short film from my travels.  I have converted the original MOV video files into WMV files, and I have also downloaded the K-lite codec package, but when bringing the videos into movie maker they still don't work, when I hit play the screen is just black? Any help greatly appreciated! Thanks