DTW Import of Service Items

Experts,

I need your guidance on DTW of service items. I have created Service Item Group and I am trying to import DTW file. I have set the ItemClass to 1 (Service). When I import my file, I get the following error:

Service Category is missing. OITM.ServiceCtg Application defined or object defined error.

I notice that the template has only Service Group field and not Service Category field. So I browsed through maintain interface of oItems and could not find service category field. Am I missing something?

Please let me know how to proceed further.

Thanks,

Arun