Diagnosis
A mapping rule is defined in the method. Before reading the source data,
the system maps the data inversely to derive the source selection fromthe target selection. However, the resulting source selection is empty.This is often caused by the use of unsuitable mapping rules.

System Response
The system cannot read the source data.

Procedure
Examine the mapping rules with regards to any complex logic contained in
condition, reassignment, or complex move operators. In particular, makesure the inversion of each mapping rule does not produce conflictingresults.