"New Lync Meeting" outlook Calendar Button with Citrix

Hi, I'm just in the middle of a new 2013 deployment. We run the Lync 2013 client on local computers and Outlook is delivered Via centralized Citrix.
Even with Lync installed on the citrix servers, We can't get the 'New Lync meeting Button' working in outlook. There is local HTTP breakout so when I manually click the Unique Link in Citrix the Local Lync client kicks in which is great. The last peice is just getting this button to appear in Outlook Citrix.

Any ideas how to get that button working?

Craig