Last delta incorrect. A repeat must be requested.

Hi all,

I'm getting this error for a process in process chain "Data target 0MATERIAL still includes delta request REQU_006HF7SP4BVY9FS5ZMWK980B1. If the repeat is now loaded, then after the load there could be duplicate data in the data targets. Request the repeat? Last delta incorrect. A repeat must be requested. This is not possible.

Plz guide how can i resolvethis issue, as i'm very new to SAP BI.