Simple Validation

I'm trying to write some validation for a field called Propid, in a form called qSearch. Basically if there's nothing in Propid, or it is says "ref no.", I want to alert the user, otherwise, I want the form to submit.

Here's what I have at the moment:

Code:


<script>
function checksearch()
{

if (qSearch.Propid.value!="ref no." )
{
alert ("Select reference number" );
qsearch.Propid.focus();
return;
}
if (qSearch.Propid.length != 0)
{
alert ("Select reference number" );
qSearch.Propid.focus();
return false;
}
}
}