Plugin order, can't get S2member variables

We have developed a plugin that uses variables set as custom fields in S2Member but it gets a function not found error. We believe it is because out plugin is loading before S2Member. Is there a way to force your plugin to load first?

Thanks
Rob

Just wanted to add this information to see if it helps:

We are trying to use the S2 shortcodes in a plugin while it loads. However, it is returning the following error:
Fatal error: Call to undefined function is_user_logged_in() in /home/fresh/public_html/wp-content/plugins/s2member/includes/classes/sc-gets-in.inc.php on line 64

How can I use the S2 shortcodes in a plug-in when it is being loaded and initialized?
THanks

It would have to load after s2Member or the s2 functions/shortcodes would not be defined before. If you’re using a hook, [hilite mono]wp_loaded[/hilite] may be a good one to use. http://adambrown.info/p/wp_hooks/hook/wp_loaded

Thanks Cristian,
this got us in the right direction and in the end we used this plugin reorder thing to fix the issue:
http://reveloper.com/wordpress-plugins-order-plugin/

this is resolved. Thanks for your help.

Excellent! Thanks for the update. :)