How to restrict Segment 1 & 2 at distribution level in AP and AR for each OU

Hi All,

Our client has two Operating Unit and there are separate responsibility of AP and AR for each Operating Unit. We want to restrict the Segment 1 and Segment 2 values in each AP and  AR responsibility for the corresponding Operating Unit,

i.e. In AP invoice of OU 1 we are able to select the segment 1 and segment 2 of OU2 as of now which we want to restrict.

Though we have created the security rule but it is not working at distribution level 

Pls suggest how can we do so.

Thanks

Abhimanyu