Hi Nick,
Please have a look at the following kb article in order to work with two different versions of essential studio.
http://www.syncfusion.com/support/kb/studio/Default.aspx?ToDo=view&questId=36Could you provide us the details about the Syncfusion dlls that your project refers and the studio version you are using? This will help us to provide you with a solution.
Please let me know if you have any queries.
Thanks,
Ramu