Combo fields not getting sent to POST

I have a form with some combo fields and other normal HTML inputs. When the form is submitted only the non-combo fields are submitted as POST variables, the combo fields are not submitted.

If I comment out the lines that make the combos, so the fields are HTML selects then the values are correctly sent.

I have checked to make sure that a value is being correctly set in the hidden input for each combo but still nothing is coming through.

Any idea what might be going on here because I’m stumped?

I have resolved this myself now - it was due to invalid HTML tag nesting.