why is this error happening

#Include <File.au3>
#include <IE.au3>
_IEErrorHandlerRegister ()
_IEErrorHandlerRegister ("MyErrFunc")
$oMyError = ObjEvent("AutoIt.Error","MyErrFunc") 

global $cpuserid

$WshNetwork = Objcreate("WScript.Network")

; var defined here
$cpuserid = $WshNetwork.UserName


; t
Func MyErrFunc()
   
 $trackerid1 = $cpuserid & @crlf   ; line 962
 $trackerid2 = $test1 & @crlf
 $trackerid3 = $test2 & @crlf
 $trackerid4 = $test3 & @crlf
 $trackerid5 = $test4 & @crlf
 $trackerid6 = $test5 & @crlf
 $trackerids = $trackerid1 & $trackerid2 & $trackerid3 & $trackerid4 & $trackerid5 & $trackerid6
 
	MsgBox(0, "", "err.number is: " & @TAB & $omyError.number & @CRLF & _
		"err.windescription:" & @TAB & $omyError.windescription & @CRLF & _
	   "err.description is: " & @TAB & $omyError.description & @CRLF & _
	   "err.source is: " & @TAB & $omyError.source & @CRLF & _
	   "err.helpfile is: " & @TAB & $omyError.helpfile & @CRLF & _
	   "err.helpcontext is: " & @TAB & $omyError.helpcontext & @CRLF & _
	   "err.lastdllerror is: " & @TAB & $omyError.lastdllerror & @CRLF & _
	   "err.scriptline is: " & @TAB & $omyError.scriptline & @CRLF & _
	   "err.retcode is: " & @TAB & $omyError.retcode & @crlf & _
	"computer tracker: " & @tab & $trackerids)
	exit
EndFunc ;==>_ErrFunc
 

>"C:\Program Files\AutoIt3\SciTE\..\autoit3.exe" /ErrorStdOut "C:\Documents and Settings\xxxxxxx\Desktop\autoit scripts\mchprocess\mchproc1.au3"  
C:\Documents and Settings\xxxxxxx1\Desktop\autoit scripts\mchprocess\mchproc1.au3 (962) : ==> Variable used without being declared.:
$trackerid1 = $cpuserid & @crlf
$trackerid1 = ^ ERROR