I'm having a hard time understanding exactly what you're doing. Can you post an example? Also, can you try it interactively with one of the sample data tables, like Big Class, to see if it's a general problem or related to your data?
I tried this with Big Class and it worked.
// Open Data Table: Big Class.jmp
// → Data Table( "Big Class.jmp" )
Open( "$SAMPLE_DATA/Big Class.jmp" );
// Data table summary
// → Data Table( "Big Class By (sex)" )
Data Table( "Big Class.jmp" ) << Summary(
Group( :sex ),
Mean( :weight ),
Freq( "None" ),
Weight( "None" )
);
// Update data tables
Data Table( "Big Class.jmp" ) << Update(
With( Data Table( "Big Class By (sex)" ) ),
Match Columns( :sex = :sex ),
Add Columns from Update Table( :"Mean(weight)"n )
);
// Select where
Data Table( "Big Class.jmp" ) << Select where( Round(:"Mean(weight)"n, 1) == 100.9 );
-Jeff