Scripting Problem

I'm having trouble getting a simple Hide/Show script to work. I keep getting this error when I try to enter the script to the "On User Action" section:

Error in statement at line number 3
The Left expression is of type STRINGLIST and the right expression is of type STRING and the operator == is not valid here

Here is the script I'm using:

if(input.projectType=="Print")
{
show Quant_Print;
}

Please help.