As you told every time you get "Select Catagory" in your dropdown boc.
I think you are calling this
fillDrpImageCatagory()
method at page Load .if its so then check for
if (!IsPostBack)
{
fillDrpImageCatagory();
}
and also in your button click
protected void BtnSubmit_Click(object sender, EventArgs e)
{
here first check for your dropdown box value
if(DrpImageCatagory.Selectedtext =="--Select Catagory--")
{
..... your message
return;
}
path = Server.MapPath("~/Images/");
int Image_Catagory = Convert.ToInt32(DrpImageCatagory.SelectedValue.ToString());
int Image_type = Convert.ToInt32(RadioImageType.SelectedValue);
con.Open();
}