FileUpload.SaveAs is configured to require a rooted path. but "http:// --- is not a rooted path

Hi Friends
when i am uploading image to http://filepath i got the 
The FileUpload.SaveAs Method is configured to require a rooted path but http:// filepath is not a rooted path
my code is as follows
If (Fileupload.HasFile)
 Then
Dim filepath As String = http://filepath/
FileUpload.SaveAs(filepath & String.Format("datafield_{0}_b.jpg", textbox.Text))
End If
Please help me
Thanks
Rama 
 
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