I am using PhantomJS to execute JS code on a webpage to automate a script for me, In this example I am trying to login through this webpage. It is kinda not like ordinary web logins, it uses JS as a submit button not a FORM.
so anyways here is the problem i am facing.

as you can see. it actually submited the page. the problem is as you can see the values of Username and Passwords were not added to the webpage. I am using this:
document.getElementById("txtUsername").vlaue="plaplapla";
document.getElementById("txtPassword").vlaue="plapalpla";
HTML code for Login :
<a id="btnLogin" href="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("btnLogin", "", true, "", "", false, true))"><b>Login</b></a>
HTML code for Username and password :
<input name="txtUsername" type="text" id="txtUsername" style="width:190px;" /><br>
<input name="txtPassword" type="password" id="txtPassword" style="width:190px;" /><br>
Also, I have no access to the HTML to change it. I will be using JS to do all the work.
any Ideas ?