Unable to Read/Set Text Box in ASPX Web page using Javascript

Hi,

Am using the below code to popup a modal dialog box.
I got the value back from the child window to the parent window.
Now i want to assign the value to one of the text boxes on the parent window.

Before that i was just checking the value in the text box and am getting an error message that document.form... is null or object not reference.

Can someone help me out in reading and setting the value to/from the parent page's text box.

I have tried with many combination of the javascript like:
document.forms[0].elements[txtTitle].value
document.form1.txtTitle.value

and few others....


Here is the code

*****************************************************
Response.Write(" <script language=""javascript"">")
Response.Write(" {")
'Response.Write(" var strReturn; strReturn=window.showModalDialog('child.aspx',null,'status:no;dialogWidth:370px;dialogHeight:220px;dialogHide:true;help:no;scroll:no');if (strReturn != null) document.getElementById('txtTitle').value=strReturn;")
Response.Write(" var strReturn; strReturn=window.showModalDialog('child.aspx',null,'status:no;dialogWidth:370px;dialogHeight:220px;dialogHide:true;help:no;scroll:no');")
Response.Write(" alert(document.frmMaterialRequest.elements[txtTiltle].value); }")
Response.Write(" </script>")
*********************************************

Thanks in Advance.