Plugin for article doesn't seem to work in J 2.5.1

I followed the instructions closely, turned on the plugin and inserted {pmform 1} into my article, yet it doesn't work. When I remove the code my page appears but when I paste the code back my page does not appear. When I change the number of the form, I get an error saying This form is not yet published.

This is Joomal 2.5.1
Using the RocketTheme template Radiance.

Can there be a problem with the plugin?

Hi

Could you please let me know the version of Payment Form you are using on your site ?

Regards,

Tuan

1.8