Substitution rule does not work in SAP CRM

Hi,

In our client, we have work flow set up for substitutions. Manager A has specified B as his substitute for approving work flow items during his absence. I checked the table T77S0, WFLOW AUTOF is set to 'X'. I checked the table HRUS_D2, here the entry shows as 

User   User   Start date         End date                   Substitute profile            Substitute Active

A          B      03/10/2014        01/01/9999                0001                                    X

However B is not able to receive the workflow items of A. When I tried to forward using SWIA, then B is getting workflow items. Not sure, why the substitution is not working. User A has set up workflow substitute in SAP CRM Web UI.

Any suggestions to resolve this will be greatly appreciated.

Thanks.

With regards,

Ravi