PO rejection mail is not triggering to the po creator

Hi Experts,

whenever a PO is rejected, the rejection intimator mail doesnot come to the PO creator(Wf_initiator). What may be the reason?

Actually it is not able to find any agents for that although according to the settings the workflow initiator should be the agent, but it is not determining the same. Can you help me on the same

Thanks

Raj