In older TYPO3 versions using IE8 context meny in BE doesn't work. 

This bug is described here.

The compatibility mode in IE8 can be used as a workaround for this problem.

When working in the typo3 backend just switch the compatibility mode in IE 8 on and clickmenu should work fine.

To do this select in IE8 menu Tools->Compatibility view and relogin into typo3 BE