Hello,
Use the ASP.NET ValidationGroup Property
Example:
<asp:textbox id="tb1" runat=Server />
<asp:requiredfieldvalidator id="ReqField1" controltovalidate="tb1"
validationgroup="valGroup1" errormessage="Required" runat=Server />
<asp:ImageButton id="Button2" causesvalidation=true
validationgroup="valGroup2" ImageUrl="img.gif" runat=Server />
Hope it will Help You.
Thanks,
Pankil