FM for BOM explosion not defined on RFC destination

What causes this issue?

The function module has not been defined on the receiver system in REA
Customizing (entry for key <LB>SAPMJ7LM</>/<LB>1</> in
the <LS>FB Name CustEx</> field is blank).

System Response

The BOM will not be exploded.

How to fix this error?

Maintaint the entry in <DS:TRAN.J7LRRE711000150>REA Customizing</>.

Procedure for System Administrators

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

How can this happen?

<LB>J7LBAPI_REABOM_READ</>

Error message extract from SAP system. Copyright SAP SE.