Item categories in agreement and requisition incompatible

What causes this issue?

The <GL:item_category>item category</> &V1& in the
<GL:purchase_requisition>purchase requisition</> and the item category
&V2& in the <GL:outline_agreement>outline agreement item</> to which
this requisition was assigned are incompatible or not defined.

How to fix this error?

You can reset the assigned outline agreement item by entering "!" as
outline agreement or item number. If the assignment is to remain as it
is, please read on.
Are the numbers of the outline agreement and the item correct?
Have you entered the correct item category in the purchase requisition?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

If so, please note the <GL:document_type>document type</> or the item
category of the purchase requisition or the assigned outline agreement.
First check the relevant entry in table T161A and then establish the
following:
Is the combination of document types/item categories defined?
Are <GL:release_order>contract release orders</> defined?
If an account assignment category is entered in the purchase
requisition item, are items with account assignment defined in table
T161A?
If the answer to any of the points 1, 2 or 3 is "no", you cannot assign
the purchase requisition to the outline agreement at present.
DEFINE &OBJEKTE& = 'Document types for purchase requisitions'
INCLUDE NA_EINK_CUST
Do you wish to display the Implementation Guide (IMG)?
<DS:SIMG.SIMG_CFMENUOLMEOMEB>Define number ranges and document types</>

Error message extract from SAP system. Copyright SAP SE.