Issue can not save

Dear All

When saving an issue I get folllwing error messages:

Error Message:
Error
Issue "General Issue": Mandatory field "" must be filled (Project Manager)

Error
Issue "General Issue": Mandatory field "Position" must be filled (Project Manager)

Error
Issue "General Issue": Mandatory field "Initiator" must be filled (Project Manager)

Error
No changes were saved

But there is no fields like "Position" on issue interface. Can you help to locate the problem?

Regards

Jimmy