Fixed pegging in GATP

Hi Experts,

    We are using SCM7.0. In GATP, we would like to use the result from planning run, so CTM planning run will create supplys and fixed pegged to demand. During GATP check, we would like to use the pegged supply to do check.

     In scope of check, we have already configured as 'consider both manual and automatic fixed pegging'.

     In below example, the sales order is fixed pegged to a deployment orders which is available on 2/27. But during GATP check, this sales order is still using the earlier PR (which is available on 2/16) to confirm and schedule. My expectation is the sales order should use the fixed pegged deployment orders as the supply and ATP check based on that. Is this how fixed pegging supposed to work? What do I miss here?

thanks,

Wenyan