Help needed while performing a GATP check on a sales order

Hi Team,

I am trying to perform a GATP check on a line item for a Sales Order from the R3 system. When I select the line item of the Sales Order and click on the "Availability screen" i.e. on the weights symbol, the control is not going to the APO system from the R3 system and am unable to see the ATP results screen of APO. The material is made as ATP relevant and hence the ATP check has to take place in APO. In my case, I am not getting this desired screen.

Please help me regarding this issue.

Thanks in advance for the help and for your time.

Thanks & Regards,

Srikanth.