Type Mismatch error.

I'm receiving a type mismatch error , line 30, char 2 on my HTA, Can someone give me a hand? I would really appreciate it! Thank you in advance!
code is as follows:
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<HTML>
<HEAD>
<TITLE>© 2012 - UMMC</TITLE>
<HTA:APPLICATION
APPLICATIONNAME="HTASetInstallOS"
ID="objNewOS"
VERSION="1.0.0"
BORDER="thin"
MAXIMIZEBUTTON="no"
MINIMIZEBUTTON="no"
SINGLEINSTANCE="yes"/>
</HEAD>
<SCRIPT LANGUAGE="VBScript">

Sub Window_OnLoad()
' Set Window Size and Location
Window.resizeTo 450,225
Window.moveTo (screen.width - document.body.clientwidth)/2, (screen.height - document.body.clientheight)/2

' Set TSProgressUI Object
Set objTSProgressUI = CreateObject("Microsoft.SMS.TSProgressUI")
objTSProgressUI.CloseProgressDialog()
End Sub

Sub SetInstallOS()
' Set TSEnvironment Object
Set objTSEnvironment = CreateObject("Microsoft.SMS.TSEnvironment")

' Set Task Sequence Variable InstallOS to XP which is 2, or W7 which is 1
If Radio = "XP" Then
objTSEnvironment("InstallOS") = "2"
ElseIf Radio = "W7" Then
objTSEnvironment("InstallOS") = "1"
End If

' Close Window
Window.Close()
End Sub

</SCRIPT>
<BODY>
<TABLE BORDER='0' WIDTH='100%' ID='AppTable' STYLE="font:12 pt calibri;table-layout:fixed">
<TR><TD STYLE='font-size:16pt' COLSPAN='3'><B>Operating System Choice</B></TD></TR>
<TR HEIGHT='47'><TD ID='YesNoLabel' COLSPAN='2' VALIGN='top'>Select Operating System to be installed.</TD>
<TD ID = 'OSVersionBox' COLSPAN='1'><input type="radio" name="Radio" value="2">Windows XP<BR><input type="radio" name="Radio" value="1">Windows 7</TD></TR>
<TR HEIGHT='47'><TD COLSPAN='2'></TD>
<TD COLSPAN='1'><BUTTON style="width:120;height:25" input id=runbutton name="Ok_button" onClick="SetInstallOS">Ok</BUTTON></TD></TR>
</TABLE>
</BODY>
</HTML>

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Any ideas??