Selecting multiple rows on an EpicCombo

I have inherited a customisation that makes use of this Infragistics code example

Selecting multiple values in a combo

It works fine in our 10.1.400x system but doesnt work in our new 10.2.400 test system.

The check boxes down the left side dont appear in the drop down.

As far as I can tell both smart clients version are built using the same version of Infragistics toolset

Anyone else used this technique?