Unable to carry out interest rate fixing

What causes this issue?

Within gap analysis, the system encountered an error in the variable
interest rate reference for a bank transaction.
The variable interest rate reference is: &V1&
The identity of the financial transaction is contained in the next
error message.
The system may not have been able to carry out the necessary
calculations.

System Response

Not all variable interest rates were fixed.

How to fix this error?

Check the variable interest rate specified.

Error message extract from SAP system. Copyright SAP SE.