Double Click not working?

Double Click not working?

Hi, I'm accessing my Mac mini from iPad Air via both local and remote settings. 
MacOS Lion ipad IOS 8.
Some time ago (within last 6 months - was using IOS 6) the ability to open a folder on the Mac by double clicking on it dissapeared. Now the only way to do it is to use the pointer and double click. This works so I do have the functionality, but I need to get the pointer out everytime which is a nuisance.

Any ideas?