[Solved] ASP.Net Error: Error converting data type nvarchar to numeric

Error converting data type nvarchar to numeric.

On line sdr.Read();

protected void Button1_Click(object sender, EventArgs e)
{            
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT Id, vst_nm, idtyp,idnm,fa_hu_nm,gndr,phn,vstd_dt,crnt_add,pur_pos FROM vstr2 WHERE idnm = " + txtconfirmpass6.Text.Trim() + ""))
        {
            cmd.CommandType = CommandType.Text;
            cmd.Connection = con;
            con.Open();
            using (SqlDataReader sdr = cmd.ExecuteReader())
            {
                sdr.Read();
                txtcurrentpass.Text = sdr["Id"].ToString();
                TextBox2.Text = sdr["vst_nm"].ToString();
                txtconfirmpass.Text = sdr["idtyp"].ToString();
                txtconfirmpass6.Text = sdr["idnm"].ToString(System.Data.SqlDbType.Decimal);
                txtconfirmpass0.Text = sdr["fa_hu_nm"].ToString();
                txtconfirmpass1.Text = sdr["gndr"].ToString();
                txtconfirmpass3.Text = sdr["phn"].ToString();
                txtconfirmpass2.Text = sdr["vstd_dt"].ToString();
                txtconfirmpass4.Text = sdr["crnt_add"].ToString();
                txtconfirmpass5.Text = sdr["pur_pos"].ToString();
            }
            con.Close();
        }
    }            
}

CREATE TABLE [dbo].[vstr2] (
    [Id]                 INT            IDENTITY (1, 1) NOT NULL,
    [emp_id]             NVARCHAR (10)  NULL,
    [emp_nm]             VARCHAR (500)  NULL,
    [dept]               VARCHAR (100)  NULL,
    [vst_nm]             VARCHAR (1000) NULL,
    [idtyp]              NCHAR (1000)   NULL,
    [idnm]               NCHAR (1000)   NULL,
    [fa_hu_nm]           VARCHAR (1000) NULL,
    [gndr]               VARCHAR (50)   NULL,
    [phn]                NCHAR (12)     NULL,
    [crnt_add]           VARCHAR (5000) NULL,
    [pur_pos]            VARCHAR (5000) NULL,
    [vstd_dt]            DATE           NULL,
    [is_dlt]             VARCHAR (3)    DEFAULT ('No') NULL,
    [is_vstd]            VARCHAR (30)   DEFAULT ('No') NULL,
    [cisf_out_flag]      VARCHAR (3)    DEFAULT ('No') NULL,
    [cisf_in_flag]       VARCHAR (3)    DEFAULT ('No') NULL,
    [cisf_out_flag_time] VARCHAR (30)   DEFAULT ('No') NULL,
    [cisf_in_flag_time]  VARCHAR (30)   DEFAULT ('No') NULL,
    CONSTRAINT [PK_vstr2] PRIMARY KEY CLUSTERED ([Id] ASC)
);