Items Rename Problem In Anvil

I don't know if anyone else has also got this problem but I was about to rename an item for something i was doing but when i tried to name it in an anvil I realised that It would not let me click on the rename part of the anvil to rename it, so what i then tried to do was name a load of different items including name tags but none of them would be renamed either. I tried to rename items in the over world, end and nether but none of these will work so I am guessing that there is something wrong with anvils unless this is intentional.