Equipment & does not exist

What causes this issue?

You entered an equipment number that does not exist in the system.

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?

Check your entry. If you entered the wrong number by mistake, overtype
it with the correct number. If you do not know the correct number,
select the desired piece of equipment using the input help.

Error message extract from SAP system. Copyright SAP SE.