#MULTIVALUE error in crosstab with aggregate functions and variables

I have a crosstab table in a report I converted from DESKI, which works fine.

I have followed the suggestion to use aggregations and created a variable but I still get #MULTIVALUE error on some rows:

As you can see, one column with the error uses =Sum([SOH] In ([iteminfo2].[Itemnum] ;[iteminfo2].[Location]))

SOH in turn is a measure variable with the code: =Sum([Curbal] In ([iteminfo2].[Itemnum] ;[iteminfo2].[Location]))

What can  do to resolve the #MULTIVALUE error? Apparently, I can't use "Avoid duplicate row aggregation" option on the crosstab and I have to use a crosstab.