get sql data based on logged in user

[fozo]

i am using Visual Studio 2010 professional and SQL server 2008 R2 expresswhat i am trying to do is detect who is the logged in user and display their detail in a gridview. the logged in user has used asp.net authentication, i have allowed users to access the page using the login process, they have the "user" role set to allow. the admin account can view all users in the account from a gridview, but i also want a logged in user to see their own details in the members section.this is shown in the code-behind\[code\]Protected Sub Page_Load(sender As Object, e As System.EventArgs)Session("MemberDetails") = User.Identity.NameEnd Sub\[/code\]this is in the main page\[code\]<asp:Gridview><Columns><asp:BoundField DataField="username" HeaderText="username" /><$ many more fields here--$></Columns></asp:GridView><asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT username, salutation, fname, sname, address, suburb, postcode, dayphone FROM member WHERE (username = @username)"><SelectParameters><asp:SessionParameter Name="username" SessionField="MemberDetails" /></SelectParameters></asp:SqlDataSource>\[/code\]all of it should work but instead i get a blank page.