No matrix has been defined yet

What causes this issue?

The function you chose is used to display or edit a matrix. However,
first you have to create a matrix.

System Response

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

How to fix this error?

Select two characteristics for which you want to create a matrix.
Create a matrix using the <LS>Extras</> menu.

Error message extract from SAP system. Copyright SAP SE.