Input string was not in a correct format.Couldn't store <> in CustStdCode Column. Expected type is [Resolved]

Hi,

in my coding i found this error.can you please help me.
Error:
Input string was not in a correct format.Couldn't store <> in CustStdCode Column. Expected type is Int32.
private void btn_new_Click(object sender, EventArgs e)
{
DataRow newrow=_datatable .NewRow ();
newrow ["custname"]=txt_customername .Text ;
newrow ["custaddress"]=txt_customeraddress .Text ;
newrow ["custcity"]=txt_customercity .Text ;
newrow ["custstate"]=txt_customerstate .Text ;
newrow ["custstdcode"]=txt_stdcode .Text;//error:Input string was not in a correct format.Couldn't store <> in CustStdCode Column. Expected type is Int32.
newrow ["custphoneno"]=txt_phoneno .Text ;
newrow ["custmobileno"]=txt_mobileno .Text ;
_datatable .Rows .Add (newrow );

Best,
Sudheep. [Resolved]