Quantity Contract

Hello SAP Gurus,

i am facing a problem by trying to raise a Quantity contract. Before raising it i first went to VA41 to operate a Master contract with the doc type GK which will serve to create with reference a Quantity Contract. By now saving my Master contract i got a opened error Window as "No control entry for SAP GTS. Call exits for Document type GK".

Could plz somebody help me to solve this error?

Thanks in advance & Reward guaranteed