Hi Manoj,
You should check to make sure that the data source has a repeating node for the parent group of the file attachment field and that the binding to the table in the view is correct. You can delete the table in your view and drag the repeating parent group over to the view from the data source and it will automatically create a table with the correct binding.
Please also verify that you are using File Attachment control (and not Picture control). MOSS 2007 (IPFS) doesn't support picture controls for browser-enabled forms.
Also, verify that you are using default web-browser, not hosting InfoPath in Form Control in Web Browser. If you are hosting the InfoPath Form Control in a Web Browser, you may have to add enctype="multipart/form-data" to the <form> HTML tag in ASP.NET page source code.
Hope this helps