Web-to-Lead Lead Not being Created – Capture Page: Not available.

If you Web-to-Lead form is not creating leads you may want to enable debugging in your form. Add the following lines to your html page:

<input type="hidden" name="debug" value=1>
<input type="hidden" name="debugEmail" value="youremailaddress@email.com">

When you click submit you may get the following message:

Reason: Your Lead could not be processed.
null
    Lead Capture Page: Not available.

Record Information:

    00Ng0000000OIjv = asdasdasdsad
    city = Test City
    company = Test Company
    debug = 1
    debugEmail = tmichels@rocketlawyer.com
    email = testmail@testmail.com
    encoding = UTF-8
    first_name = Test Name
    last_name = Test Last Name
    lead_source = Employee Referral
    oid = 00Dg00000008e4p
    phone = 4084213722
    recordType = 012g00000004IkA
    retURL = http://
    state = Test State
    submit = Submit

Solution:

Change your action URL by specifying test for Sandbox or your instance name for Production eg: na4
Sandbox will look like this:
<form action="https://test.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8" method="POST">

Production will look like this:
<form action="https://na4.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8" method="POST">