Help with getting setNodePossiblePropertyValues to initialise dynEnum

I have created a OnReady hook to initialise some attributes for an activity.
The code looks up an Sql database to find customer names relevant to the user's branch and should make that list available as the possible values of the CustomerName dynEnum.

The SQL part works OK, and I do
prjSession.setNodePropertyPossibleValues(nodeName,"CustomerName",customerList);

But when the form opens the dropdown list shows only the value I put in there from Proed.

I have include the Java here.

myHookOnReady.java

Can anybody see what I am doing wrong?