'Purchase requisition' cannot be selected manually. in AX 2012

Hi friends,

Requests for quotations > All requests for quotationsType, when i select the Purchase type “‘Purchase requisition’ cannot be selected manually.” this error is shown. Can any one tell me how to solve this issue.

Regards,

Subbu

This is cannot be set manually, This value will be set by the AX when the RFQ is created from purchase requisition.