Join Table confusion

I have a view in which I would like to set values for three separate
join tables. Everything seems to work fine from the console but when
I use the _form.rhtml it only inserts values into the first join
table.

This is what I have in my _form.rhtml

<p>
  <label for="technicians">Technicians:</label><br />
  <select id="technicians" name="technicians[]" multiple="multiple"
size="5" style="width:250px;">
    <%=
options_from_collection_for_select(@all_technicians, :id, :name,
@selected_technicians) %>
  </select>
</p>

<p>
  <label for="computers">Computer Models:</label><br />
  <select id="computers" name="computers[]" multiple="multiple"
size="3" style="width:150px;">
    <%=
options_from_collection_for_select(@all_computers, :id, :model,
@selected_computers) %>
  </select>
</p>

<p>
  <label for="licensed_programs">Licensed Software:</label><br />
  <select id="licensed_programs" name="licensed_programs[]"
multiple="multiple" size="8" style="width:200px">
    <%=
options_from_collection_for_select(@all_licensed_programs, :id, :name,
@selected_licensed_programs) %>
  </select>
</p>

The html that is generated looks good too

<p>
  <label for="technicians">Technicians:</label><br />
  <select id="technicians" name="technicians[]" multiple="multiple"
size="5" style="width:250px;">
    <option value="4">Albert Martinez</option>
<option value="6">Chris Sanchez</option>
<option value="3">Luis Arvizu</option>
<option value="5">Orlando Garcia</option>
<option value="2">Richard Martinez</option>

<option value="1">Thao Dang</option>
  </select>
</p>

<p>
  <label for="computers">Computer Models:</label><br />
  <select id="computers" name="computers[]" multiple="multiple"
size="3" style="width:150px;">
    <option value="1">Dell GX240</option>
  </select>

</p>

<p>
  <label for="licensed_programs">Licensed Software:</label><br />
  <select id="licensed_programs" name="licensed_programs[]"
multiple="multiple" size="8" style="width:200px">
    <option value="1">VIZ</option>
  </select>
</p>

I would guess I'm missing how/where it's being passed to
ActiveRecord. Although technicians works and I have the subsequent
two constructed in a similar fashion.

Any help would be greatly appreciated.

Thanks,
Glen

Thank, I appreciate the reply. I was being stupid though and had a
couple of pieces missing in the controller.

Will <%= select :model, :technicians, @all_technicians %> generate a
multi-select? i.e. does it generate based on the relations defined in
the model?