Message Postings: add a new validity period ... from BAPI BAPI_RE_CN_CHANGE

Hello,

I'm getting the message "Postings: add a new validity period for ..." when i try to insert a partner in a contract using the BAPI BAPI_RE_CN_CHANGE. The requirement is to split the period of each one and to relate them with the Payment tab respectively.

Actually, the error message is RETMCA 026.

Here, I'm attaching an image.

Originally my contract have two partners.

But,

I want to add new one (3000005), like this:

Please, If you have any idea about it, i would be grateful.

Thanks.

Regards.