Music Not added in iTunes

Friends,

This is my first post and really not sure if i'm positng necessary information.

However, My problem is adding a .MP3 to itunes

1. I have a Windows Phone 8.

2. Downloaded some music through Nokia Music

3. Copied them to my Windows 7 PC

4. Trying to add the .MP3 to itunes (having iTuens 11.1.5.5 for Windows) but not getting added. I see that was copied to a "Not Added" forlder.

I need to copy the MP3 to itunes to sync with my other apple devices.

Please note I have other .MP3 which gets added without any problem. My Windows Phone setup to sync music with iTunes

I hope i've given enough information to start with.

Appreciate your help and support.

Thanks,

Viswe