Why is this expression giving me a syntax error?

Why is this expression giving me a syntax error?

Hi,

I'm trying to match an input with an id ending in "dlNum".  I have this expression ...

$( "input[ @id $= 'dlNum' ]" ).val(licenseNumber);
   
but on Mac 10.5.6 Firefox (latest version), I'm getting this error:

uncaught exception: Syntax error, unrecognized expression: [ @id $= 'dlNum' ]

What is the correct syntax to use to match an id ending in an expression?  Thanks, - Dave