Required Field Validator for images (fileupload)

[pieandpeas]

Hi, i've got a required field validator set to check if a file being uploaded (via a fileupload control) is a valid image (jpg or gif),

it works , to a point,

When an item is selected which isnt an image, e.g text.doc, it automatically brings up the error message, but if the file IS an image, it waits until you click Submit, before bringing up the same error message (but when it is an image, it actually uploads it fine),

so what i'm trying to say is, can anyone spot a problem with my code, so that it will stop showing this error message even though it is uploading ok.

Thanks

<asp:RegularExpressionValidator 
id="FileUpLoadValidator" runat="server" 
ErrorMessage="Upload Jpegs and Gifs only." 
ValidationExpression="^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))(.jpg|.JPG|.gif|.GIF)$" 
ControlToValidate="FileUpload1">
</asp:RegularExpressionValidator>

and

        If FileUpload1.HasFile Then
 
            FileUpload1.SaveAs("C:\uploads\" & 1429 & ".jpg")
 
        End If