Change Password using Stored Procedure

protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { Session["siteid"] = "siteid"; if (Session["siteid"] != null && Session["siteid"] != "") { string siteid = Session["SiteID"].ToString(); } } } protected void btnSubmit_Click(object sender, EventArgs e) { try { con.Open(); { string OLdpassword = txtOldPassword.Text; if (OLdpassword == txtOldPassword.Text) { if (txtNewPassword.Text == txtConfirmPassword.Text) { Session["siteid"] = ToString(); SqlCommand cmd = new SqlCommand(); cmd.Connection = con; SqlDataAdapter da = new SqlDataAdapter(); cmd.CommandText = "UpdatePassword"; cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.AddWithValue("@SiteID",Convert.ToInt32(Session["siteid"].ToString())); cmd.Parameters.AddWithValue("@Password", txtOldPassword.Text); da.SelectCommand = cmd; DataTable dt = new DataTable(); da.Fill(dt); Session["siteid"] = dt.Rows[0]["SiteID"].ToString(); cmd.ExecuteNonQuery(); if (dt.Rows.Count > 0) { lblmsg.Text = "Password updated successfully"; } else { lblmsg.Text = "Execution error"; } } else { lblmsg.Text = "Password miss match"; } } else { lblmsg.Text = "Old password is incorrect"; } } con.Close(); } catch (Exception ex) { } } protected void btnCancel_Click(object sender, EventArgs e) { Response.Redirect("Login.aspx"); } } here is my code it gives error Error converting data type nvarchar to int.