HAScript: How do you assign an AS400 screen field value to a variable (via Variable Update Action)?

Question

From the guide, I must enter the name of the variable to be updated ($ScreenName$) into the 'Name' section, and the location string ('2,40') into the Value section. No matter what I try, the 'ScreenName' variable keeps getting changed to the literal value in that section: '2,40' (NOT the text that is in the field located in row 2, column 40). I can find no examples of a screen grab in HAScript to see what I am missing.

<HAScript name="TestHROrderList" description="asdf" timeout="10000" pausetime="300" promptall="true" blockinput="true" author="" creationdate="" supressclearevents="false" usevars="true" ignorepauseforenhancedtn="true" delayifnotenhancedtn="0" ignorepausetimeforenhancedtn="true" continueontimeout="false">

    <vars>
      <create name="$ScreenName$" type="string" value="&apos;test&apos;" />
    </vars>

    <screen name="Screen1" entryscreen="false" exitscreen="true" transient="false">
        <description >
            <oia status="NOTINHIBITED" optional="false" invertmatch="false" />
        </description>
        <actions>
            <varupdate name="$ScreenName$" value="&apos;2,40&apos;" />
            <input value="&apos;[tab]&apos;" row="0" col="0" movecursor="true" xlatehostkeys="true" encrypted="false" />
            <input value="$ScreenName$" row="0" col="0" movecursor="true" xlatehostkeys="true" encrypted="false" />
        </actions>
        <nextscreens timeout="0" >
        </nextscreens>
        <recolimit value="10000" />
    </screen>

</HAScript>

I have read the guide, and googled for anything that I could find, but I'm not having any luck finding an answer.