Can't add a Radio Button to Existing form

I have an existing form that I created for a client that has page breaks and is 9 pages long. They asked me to add a simple yes/no radio button to the form, however it will not allow me to add this to the form. I have tried simply adding it and also duplicating an existing radio button field that is within the form and not matter what it does not allow for the new field.

Any suggestions as to why this would be occurring? The form can be seen at http://syit.us/rDC22Z.

The form was originally designed with a previous version of Gravity Forms, but I have continued to update the plugin as each release was provided.

Thanks in advance for any help.

No errors on the page and I can't add any other field types either.

Thanks to everyone that posted on this thread. I figured out how to work around the issue yesterday. It seems that since I was using Google Chrome 16.0.912.63 m it would not work for some reason. I tried adding the radio button field using Firefox 9 and it worked with no problems.

So large in part, if anyone is having troubles using Gravity Forms in a particular browser, then try a different one to see if the problem still occurs.