Error when creating a Purchase Order in Buyers Work Center

Good Morning Purchasing Experts,

I am receiving an error when creating a Purchase Order in the Buyers Work
Center.

After entering the Header Information, I then click the Lines tab.

Upon selecting an Item, the screen displays the following error:
"Unexpected Error please contact you System Administrator."

Can someone please provide some clarifications/resoultion as I am new to
this module?

Thanks