I am running Mac OS X 10.7.5 and using Lightroom 5. I am creating a slideshow with music. Lightroom will let me select a music file but the Fit to Music button is greyed out. The music file I had selected was an .mpg. I have tried several other .mpg files and even an .m4a just to see if it would work but to no avail. Next to the music file there is an exclamation point in a darkened circle. When the cursor is hovered over the ! it shows the message, The selected file is not a valid music file. I was using Lightroom 3 previously with no problems and made the switch to Lightroom 5 earlier this year. Any suggestions would be appreciated.
an MPG file is a move file - not a music file. Try using an MP3. an M4A file should work as well.