conflict Hueman theme with WP eStore

hi, I absolutely love the Hueman Theme!
Just ran into an error code with WP eStore, though”

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘ot_after_theme_options_save’ not found or invalid function name in /home/tinvan3/innerdelight.com/wp/wp-includes/plugin.php on line 429

I tested the plugin in Twenty Fourteen theme and it works fine there.

Any suggestions as to how this can be fixed?

thanks heaps,
Tina