Rank Problem in Chart

[colt]

Hi,
I have a Chart-Report migrated from 8.4.1 to 10.1.1 utilizing the rank function. When I validate the report in Cognos 10.1.1, no errors were found.
But when I run the report, I get a parsing error that points to the filter in which the rank function is used. The strange thing, if I remove the chart and insert a list instead and put all items from the query to the list, then the report runs without problems.

The query itself is build up as union combining 2 other queries. One of them gets the top 10 Articles and the other on totals the rest of the Articles.
the Rank filter itself says:
rank([item1] DESC, [item2], [item3] FOR REPORT) <= 10. The error message points to position of the first ','  between [item1] DESC] ,  [item2].

As I said: if I show data in list, it shows the 11 lines and it's fine. In 8.4.1 it chart runs fine too.
I thought on putting unused dataitems of union query in chart items properties, but without success yet.

Any ideas ?