error in set col value with JSL formula

[#1]

Open( "$SAMPLE_DATA/Big Class.jmp" ); 
dt=(Data Table( "Big Class" ) << Tabulate(
	Add Table(
		Column Table( Grouping Columns( :sex ) ),
		Row Table( Analysis Columns( :height ), Statistics( Mean ) )
	)
)) << Make Into Data Table;
dt<<New Column ("total", numeric, continious);
:total<<formula(:F+:M);// this line works by itself but causes error in script

:total<<formula(:F+:M);// this line works by itself after the script but causes error in the script?

[#2 · Accepted solution]

I personally try to avoid any auto-scoping in JSL, especially when it comes to column names.  If you explicitly scope :TOTAL to DT:TOTAL then this works.  The reason for the failure is because dt is not the current data table, and the current data table does not have a :TOTAL column.

Open( "$SAMPLE_DATA/Big Class.jmp" ); 
dt=(Data Table( "Big Class" ) << Tabulate(
	Add Table(
		Column Table( Grouping Columns( :sex ) ),
		Row Table( Analysis Columns( :height ), Statistics( Mean ) )
	)
)) << Make Into Data Table;
dt<<New Column ("total", numeric, continious);
dt:total<<formula(:F+:M);// this line works by itself but causes error in script

[#3]

Thanks, and it also explains why the last line "magically" works, when I switch to the tabulate table