I'd not seen that brand of bonding paste you're using before? Is that the one that Towed used?
Given that they're a specialist company, that web site is amazingly light on details! But it looks the proper job
Here is the one that i am using.
http://www.cfsnet.co.uk/acatalog/Gravicol_2039.html
I also used that on my Spyder and it sets like rock, but takes a while to fully set.