Transferring files help

[NorfolkLion]

I have been able to drag and drop files, such as mp3's etc, from my external HD onto my imac without any problems, but now it no longer allows me too. As i try to drag a file a no entry type sign becomes visable?... i checked the "get info" on both the external and imac and it says the read and write is on!

I appreciate any help in advance

 

[theISHkid]

Double check and make sure that the locked box didn't get hit... that happened to me just today.