How to post textbox value after selecting particular checkbox

How to post textbox value after selecting particular checkbox

Here is the snippet of html code.....
1)After checking each check box the value's is posting to the database.
2)But the problem is when i checked other, i need to take the value of the
text box and it is posting the value of the checkbox instead of the
textbox value
but i don't know where i did mistake...
<form action="purchase.php" name="form1" id="form1" method="POST">
<ul class="n_ul"> <span>*</span>
What is your Primary goal?
<br>
<br>
<li>
<input name="goal" id="goal" value="Add a popular customer
service to attract/retain more customers"
type="checkbox">
</li> <span>*</span>
Popular customer Services
<br>
<br>
<li>
<input name="goal" id="goal" value="Add a turnkey revenue
sources for my location(s)"
type="checkbox">
</li> <span>*</span>
trunkey revenue source
<br>
<br>
<li>
<input name="goal" id="goal" type="checkbox" value="other">
</li> <span>*</span>
Other (Please specify below)
<br>
<br>
<input name="other" id="goal" type="text" class="new">
</ul>
</form>
Any suggestions are acceptable....