What's wrong with below code

[#1]

I've got errors on below code:

dt << New Column( "Stage",
	If( Formula( Substr( :Column 9, 1, 2 ) ) == "CP",
		Formula( Left( :Column 9, 3 ) ),
		" "
	)
);

I want to add a new Col named "Stage" besides a raw Column 9, if starts with CP get the 1st 3 letters else blank, but I've got errors 

Unexpected end of input. Perhaps there is a missing "," or ")".
Trying to parse arguments of function "New Column".
Line 207 Column 3: ►

I suspect I use Formula in wrong way, might need help here :)

Column 9	Stage
NG
CP2-NAVI12	CP2
CP1-NAVI12	CP1
NG
CP2-NAVI12	CP2

[#2 · Accepted solution]

The issue with your code is that you are not understanding the Formula element from the New Column function.  You seem to be approaching the problem thinking that each segment within your line of script that has a function, such as Substr() or Left() needs to be told that it is a formula.  Actually, the entire line of jsl:

If( Substr( :Column 9, 1, 2 ) == "CP", Left( :Column 9, 3 ), "" )

is what needs to be declared as the formula for the new column.  Thus the New Column() function needs to be specified as:

dt << New Column( "Stage",
		Character,
		"Nominal",
		Formula( If( Substr( :Column 9, 1, 2 ) == "CP", Left( :Column 9, 3 ), "" ) )
	);

[#3]

Thanks Jim, Got it :)