How to disable link button if GridView is not present in a page

I am not getting any error. The functionality is not working. I have set the LinkButton in master page to false.

Please find the code in Test.aspx.cs file

   protected void Page_Load(object sender, EventArgs e)
        {            
        }

        protected void ButtonView_Click(object sender, EventArgs e)
        {
            object obj = Session[PROJECTS_DATA_TABLE];
            if (obj != null)
            {
                GridViewProjects.DataSource = (DataTable)obj;
                GridViewProjects.AutoGenerateColumns = true; 
                GridViewProjects.DataBind();
                if (GridViewProjects.Rows.Count > 0)
                {
                    LinkButton lb=Page.Master.FindControl("LinkButtonExport") as LinkButton;   
                    lb.Visible = true;
                }
                else
                {
                    LinkButton lb = Page.Master.FindControl("LinkButtonExport") as LinkButton;   
                    lb.Visible = false;
                }
}

Test.apsx

<asp:Button ID="ButtonSubmit" runat="server" Text="Create" OnClick="ButtonSubmit_Click"/>