Web Forms :: Label Not Displaying Error Message Text

I use below code for doesn't insert duplicate data in table 

ALTER procedure [dbo].[insertestate1]
@position nvarchar(max)
,@Transfer nvarchar(20)
,@Type nvarchar(20)
,@Behcode nvarchar(10)
,@Measure varchar(20)
,@code varchar(20)

[code].....

Behind code

protected void ImageButton2_Click1(object sender, ImageClickEventArgs e)
{
string data = Server.UrlDecode(Request.QueryString["BehCode"]);
SqlCommand _cmd = new SqlCommand("insertestate1", _cn);
_cmd.CommandType = CommandType.StoredProcedure;
_cn.Open();

[code].....

now my problem is that  when it insert or didn't insert data in data base it didn't show any message in LBLERROR