Partner determination

Hi All

I have created a partner determination procedure for sales document header and included all the partner functions SP, SH, PY,BP & also contact person. I have assigned it to the order type ZOR. But when I am trying to create a sales order, the SP & SH is greyed out. when I switch the procedure to std TA, it's working.

What would be the reason ? Need quick answeres from the experts.

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Thanks