Your input field is disabled: disabled="true"
Change
<input id="piazipcode1" class="entryzip" onkeypress="return submitenter(this,event)" checked="0" disabled="true" maxlength="5" name="piazipcode1" readonly="true" type="text" />
to
<input id="piazipcode1" class="entryzip" onkeypress="return submitenter(this,event)" maxlength="5" name="piazipcode1" type="text" />
More on this:
What’s checked="0" got to do with your input field? Checked is used for radio buttons.
Use
http://validator.w3.org/ to validate your code.
