Error loading data from DS to SAP BI PSA

Hello,

We are using DS 4.1 as an ETL to push data into SAP BI 7.01 SP 07 from a SQL Server database.

We are having a random problem when loading data from DS on to the PSA Table in BW.

Sometimes at the beginning of the load the process marks an error on the BI side, although it continues loading.

The error we get is:

Ex=1 Error when opening an RFC connection

Message no. RSAR051

We have checked RFC connections from both DS and BW and they are ok.

The load job is been triggered from DS.

Any suggestions on how to solve this issue?

Thanks for your help, kind regards,

Salvador