SELECT/OPTION problem

[omegabeta]

I'm trying to select an option to make afilter of my database, but after each selection the control show me the first option.
I don't want why.

<form name = form method = post action="<%=request.servervariables("script_name")%>">
<input type="hidden" name="flag" value="177">
<select name="cboMarca" onchange=" submitform()">
<option value=177 <% if m="177" then %>selected<%end if%> >BBBBBBBBB
<option value=277 <% if m="277" then %>selected<%end if%> >PPPPPPPP
<option value=395 <% if m="395" then %>selected<%end if%> >CCCCCCCCC
</select>

Could someone help me?

Thanks