For diagnostic purposes (not to be left in the script permanently) could you please add a 100 ms delay after you send <Key PgUp>? The result would look like this:

Code:
<Template SendMasterAndSlave>
         <SendFocusWin>
                  <Key %1%>
        <Wait 100> // FOR DEBUGGING ONLY, NOT TO BE LEFT IN SCRIPT PERMANENTLY
         <Sendlabel %4%>
                  <Key %3% %2%>
<EndTemplate>
If that doesn't work, could you please say which toon is on which PC?