Full and delta loads in ODS

Hi,

Can I load both the delta and full loads to an ODS. My scenario is like this.

I have data for previous years which wnot change and data for the current year which changes. I loaded full load for previous years and tried to load initialized delta only for the current year. But when I tried that option I am getting an error which reads

Full updates already available in ODS ZODS2 ; Cannot update init./delta and activation is failing.

Is this option possible ??

( I am using BW3.5 and the data souce is 0CO_OM_WBS_7 - WBS Elements: Commitment Line Item )

thanks

Datta