what is the appropriate way of logging in asp.net ajax?

I've created the following, one thing I noticed is that this does not like the image button? It does not work with the image button. The screen is blank. Is there a way I can fix this?

 <div id="loginbox">
        <div id="AnonymousView" style="display: none;">
            <label>User Name:
            <input type="text" id="txtUsername" />
            </label>
            <label>Password:
            <input type="password" id="pwdPassword" />
            < ...