Lock owner name

We are using ARIS 9.8. I've created a script that reads from two different models, without a problem. The script then needs to create a new model, and place some of the objects from the other two models on the new model. My string looks like:

var oNewAppColDiag = oGroup.CreateModel(Constants.MT_PRG_STRCT_CHRT, nModName, LNG);

But for some unknown reason, I get the following error:

lock owner name must not be null 

Can anyone supply me with ideas on why this happens, and how I can fix it.

Thanks for your help.

Regards,

Willem