Form not working properly

I have a form and when a user submits the "submit" button, it opens another page. This kind of functionality is working when this html is in the C drive. But when I put it in the server (in our office server), when I click on the "submit" button I get "page cannot be displayed" page. Why?
Here is the code:

<form name="newcust" method="post" action="addnewcustomer.html">
<input type="text" size="23"><br>
<input type="submit" name="gonewcust" value="Add Customer">
</form>

Did you copy the addnewcustomer.html file to the server too?

Any way I figured out the problem. When I put <form name="df" method="get"> it is working. But if I put method="post" then it is not working.