Generic datasource can't update in infosource

Hi,

I've a generic datasource with delta update activated and, the field for delta is 0calday.

The problem is that when in BW I try to update with delta infopackage it doesn't allow me because "datasource can't update in infosource". Looking the "Performance assistant" it suggesto to me using an ODS.

My question is, is it really necessary to use and ODS? isn't it possible to load directly to an infosource?

Thanks a lot.

Regards.