As far as I understand (and I might be wrong about it), you can't group and sort by a new calculated field in the same statement. Here is what's stated in QlikView Help:
order by is a clause used for sorting the records of a resident table before they are processed by the load statement. The resident table can be sorted by one or more fields in ascending or descending order. The sorting is made primarily by numeric value and secondarily by national ASCII value. This clause may only be used when the data source is a resident table
Based on that, you should first group your data, and then reload the same table again in a resident load and sort it using the ORDER BY clause.
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