Suddenly Can't drag audio files to Timeline

Hello guys - been working on a piece for a week now and I just noted I can no longer drag any audio (wav) to the timeline. I can drag video no problem. I also noticed I can not drag any effects into the timeline either.

I did a Save As a few days ago and those versions are fine

I'm sure it must have been something I did!

Please help Thanks In advance Mike

Maybe your track is locked? Dumb answer maybe but it's the first place I'd look.

Are they known 'good' files? i.e. are you able to use those specific files in your other versions?

Hello thanks that's exactly what it was the audio track did not have the red outline thank you!

Mike