You define validationgroup="Test"
on your validators , and you define also this validationgroup="Test"
on your Button.
Sample
.....
<asp:requiredfieldvalidator id="NameTextBoxRequiredValidator"
controltovalidate="NameTextBox"
display="Dynamic"
text="Please enter your name."
validationgroup="ForPanel" <----------------
runat="server"/>
<asp:button id="SubmitButton"
text="Submit"
validationgroup="ForPanel" <------------------
runat="server"/>
Nota : Gets or sets the name of the validation group to which this validation control belongs.