After upgrade, Duplicate function not work

It sounds like something is wrong with how your site upgraded, or you have some sort of plugin conflict. Nothing changed with the Duplicate form functionality from prior releases.

Try re-installing Gravity Forms from scratch (download the plugin file from the Downloads page of this site, go to your Dashboard, deactivate Gravity Forms, delete Gravity Forms, re-install from the 1.5 zipfile).

If that doesn't work it's possible you have some sort of theme or plugin conflicts. You will need to check for conflicts by deactivating all plugins, testing the Duplicate functionality and if it works then activate each plugin one by one (or in groups) and test after each one until you determine which one is causing the issue.

It's possible it's a theme conflict also, you would test for that by activating the default Twenty Ten theme and seeing if the issue still occurs.

No, you won't lose your forms if you delete Gravity Forms the way I described.

The only way to lose your forms/entries is if you use the UNINSTALL option on the Gravity Forms Settings page that has the big red warning. DON'T do that.

If you send us a WordPress admin login for this site we can take a look and see what is going on so we can get it resolved. Can't debug it if we can't recreate it or see it happening. You can send this information to us via our Contact Us form and reference this forum post. Thanks!

I will email you the old release to your gmail account.

We can't reproduce the issue which appears specific to your site (probably a theme or plugin conflict that is causing this) there is no way for us to help you fix it.

The only way to help you fix it so you can use 1.5 is to let us login and see it happening so we can determine what is causing it. It wouldn't take long.