java.lang.NullPointerException while creating physical ds

Hi,

I am trying to create a physical data service using stored procedure as data
source. While creating I could select the data source from drop down and add the
required stored procedure in the list. After that when I click on next button it
gives the null pointer excepton.

For some stored procs it gives the null pointer exception but for some i could
successfully create the physical ds.
All these stored procs are from same data base.

Please help.

Thanks in advance.

Regards,