_arraybinarysearch not working

this is my file and hence the contents of the array

U3DAISC  G#23TRND test
U3DAPADD G#23TRND test
U3DAPDEL G#23TRND test
U3DAPDIS G#23TRND test
U3DAPMOD G#23TRND test
U3DBAFRM G#20TRNP prod

am trying to find U3DAPDIS.
am getting back a -1 ofr $ix and @error = 2

#include <Array.au3>
#include <IE.au3>
#Include <File.au3>
dim $testgrps[1000]

$file3 = "C:\Documents and Settings\Desktop\tstgrps.txt"
_filereadtoarray($file3, $testgrps)
_arraydisplay($testgrps)
$getgrp = inputbox("ck test","enter test group to verify")
$ix = _arraybinarysearch($testgrps,$getgrp)
msgbox(0,"",$ix & " " & @error)
exit