paging in gridview not working for first click ..pls help me

GridView1.PageIndex = e.NewPageIndex;
        string serchtext = "ClientName like '" + CName + "%' and WorkLocation like '" + Loc + "%' and JobTitle like '" + title + "%'";

        SqlCommand cmdv = new SqlCommand("Select JobId,ClientName,JobTitle,JobType,SkillsRequired,Experience,NoofPositions,Status,WorkLocation from JobsInformation", Con);
        SqlDataAdapter da = new SqlDataAdapter(cmdv);
        DataSet ds = new DataSet();
        da.Fill(ds);
        Con.Close();
        DataView dv = null;
        dv = new DataView(ds.Tables[0]);
        dv.RowFilter = serchtext;
        GridView1.DataSource = ds;
        GridView1.DataBind();