Use the Change Fulfillment Type drop-down to set the request to either Document Delivery, Purchase Request, or ILL Request, depending on if you are using Tipasa or WorldShare Interlibrary Loan
Select Save
Resend the request.
If the error persists, switch the fulfillment back to what it was originally and close the request and open a new purchase request for GetItNow.
If the error continues, contact OCLC Support with your OCLC symbol and a full page screenshot of the error message.