DataGridView Template Field Header DropDownList ID not found

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C#

ASP.NET

Inside of a datagridview I have a template column with a drop down list in the header. I've named the ddl in my asp but in my code behind it's not finding it. any suggestions?
The code is as follows:

<asp:TemplateField HeaderText="BMOS" SortExpression="BMOS">
<HeaderTemplate>
<asp:Label ID="bMOSLabel" runat="sserver" Text="BMOS">
<asp:DropDownList ID="bMOSDDL" runat="server"
onselectedindexchanged="bMOSDDL_SelectedIndexChanged">

</HeaderTemplate>

protected void bMOSDDL_SelectedIndexChanged(object sender, EventArgs e)
{
con.Open();
sql = bMOSDDL;
cmd = new SqlCommand(sql, con);
total_Gridview.DataSource = cmd.ExecuteReader();
total_Gridview.DataBind();
con.Close();
}

the bMOSDDL inside the protected void brings up the error that the name does not exist in the current context. Anyone have a solution for this?

I would also like to add that my boss doesn't even know why it isn't loading. I could really use some assistance with this. I've been able to go into the constructor and manually put the object in there and it remove the error but as soon as I run it, the web page displays the exact same error.

Thanks in advance,
Sean8084