Can't Update Members database Membership.UpdateUser

Hi

I have been having a problem updating the ASPNETDB.MDF Created by Visual Studio when creating Membership forms like login new user etc

I Have created a GridView to edit existing user in this database updating Roles works but when i try to Update fields like Email or ISApproved it is not save the changes to the database

    protected void gdvEdit_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        int intIndex = Convert.ToInt32(e.RowIndex);
     

        TextBox txtUserName = (TextBox)gdvEdit.Rows[intIndex].FindControl("txtUserName");
        TextBox txtEmail = (TextBox)gdvEdit.Rows[intIndex].FindControl("txtEmail");
        CheckBox chkEditIsLockedOut = (CheckBox)gdvEdit.Rows[intIndex].FindControl("chkEditIsLockedOut");
        ListBox lsbRoles = (ListBox)gdvEdit.Rows[intIndex].FindControl("lsbRoles");

        //Remove all Roles From User
        string[] userRoles = Roles.GetRolesForUser(gdvEdit.DataKeys[intIndex][0].ToString());
        foreach (string strRole in userRoles)
        {
            Roles.RemoveUserFromRole(gdvEdit.DataKeys[intIndex][0].ToString(), strRole);
        }

        //Replace with new selection of roles
        for (int i = 0; i < lsbRoles.Items.Count; i++)
        {
            if (lsbRoles.Items[i].Selected == true)

                Roles.AddUserToRole(gdvEdit.DataKeys[intIndex][0].ToString(), lsbRoles.Items[i].Value);
        }

        string UserName = gdvEdit.DataKeys[intIndex][0].ToString();
        MembershipUser UserDetails = Membership.GetUser(UserName);

        //Update User Details
        UserDetails.IsApproved = true;
        UserDetails.Email = txtEmail.Text.Trim();

        if (chkEditIsLockedOut.Checked == false) { UserDetails.UnlockUser(); }
        Membership.UpdateUser(UserDetails);

        //Rebind GridView
        gdvEdit.EditIndex = -1;
        Bind_gdvEdit();
    }

Any Ideas on why this maybe happing would be appreciated

Thanks
John