Thanks for reporting, I’ve not come across this bug, however – I’ll take a look at this and push out a new version 😉
OK – I’ve replicated your bug – you have either:
1) defined the following in your wp-config.php:
define( 'WP_POST_REVISIONS', false );
OR
2) another plugin is defining this constant.
I’ll amend the plugin when I get a chance to see if the constant is already defined, but in the meantime, to fix this – see if you have defined this already in your wp-config.php file (which is the most likely cause) and simply remove the entry and use the Post Control plugin option to define revisions 😉
I have neither of the two alternatives. 🙂
This is the output of grep -lR WP_POST_REVISIONS *when run in root:
wp-content/plugins/wp-cms-post-control/wp-cms-post-control.php
wp-includes/default-constants.php
wp-includes/revision.php
The constant is defiend on line 324 in wp-includes/default-constants.php
