Diagnosis
You want to search for a suitable reference module. However, in thegeneral Customizing settings for multiple references, the reusability ofreference modules setting is switched off. Therefore the system cannotcarry out the desired search.

Procedure
Check the general Customizing settings for multiple references. It isrecommended that you use reference modules that are reusable becausethis leads to a considerable performance improvement and to a reductionof data.