The likely causes of this issue are
The PIR you are trying to approve has not yet been matched
The PIR you are trying to approve has been rejected
If the PIR has not yet been matched:
Log in to Dimensions
Browse to Creditors, Match, Match Order
Find the invoice using the search filters
Double click on the invoice
Match it accordingly (seek advice from a user who usually does this process if you are unsure)
Save
Choose an approver to send the PIR to
If the PIR you are trying to approve has been rejected:
Log into Dimensions
Browse to Creditors, Match, Match Order
Tick the box for "Include Match Orders" and then find the PIR invoice using the search filters
Double click on the invoice
Unmatch it by setting all PO lines in the top half of the screen to "NO" - double click to change this
Save
Browse to Creditors, Amend Entry
Find the invoice using the search filters
Double click on it
Save
Browse to Creditors, Match, Match Order
Find the invoice using the search filters
Double click on the invoice
Match it accordingly (seek advice from a user who usually does this process if you are unsure)
Save
Choose an approver to send the PIR to
The Invoice should now be able to be approved by whoever it was sent to and the error will no longer appear.
If the Invoice is definitely matched and not rejected, please raise a new case and reference the title of this article.