I tested the mobile apps with the kassyopea theme v1.6 with WordPress 4.5.2 and the latest version 3.11.2 of wp-eCommerce. I did not run into the Fatal error, so I suspect you are running an older version of theme. Please update to the latest version and let me know if you run into the same problem.
Hi, first of all thanks for reporting this issue! It seems there is a conflict with the theme. I will try to reproduce the same error and to find a fix. Thank you!
I am uninstalling the plugin because of this registration requirement to remove the ads. It makes no sense and it is easy to swap to another plugin. You should reconsider this.
Thank you.