My name is Mercedes and I am from WPML team. We have received a request in our support forum to check on the compatibility with Side Offer. You can see it here http://wpml.org/forums/topic/plugin-not-compatible/
Let's work together in solving this problem and making your plugin compatible with WPML.
Many theme and plugin authors have joined efforts with us and have been rewarded with a sales boost. The need for a multilingual site is increasing by the day and WPML is the perfect solution for this :)
After the process is complete, we will announce it to our users and add SideOffer to our compatibility page.
You can see the happy list here
Could you please drop me a line back?