Perl scripting using external tool

Hello We are trying to use the external tool node to run a perl script. The perl script expects an input argument.  The external tool node gets the input argument from the inject variables node, but uses the variable name and not the value. How can we tell the external node tool to use the value and not the variable?

You will probably need to construct a valid set of arguments using the java edit variable node and then use this variable in the external tool node. 

See the attached screenshot for a very simple example snippet node.  The "argument" variable would subsequently be used in the external tool node.