gac - Could not load type '' (blank) error when trying to reference .NET assembly in NAV2013 -

i've created assembly want able call c/side in role-tailored client in dynamics nav2013.

i've got working locally when trying deploy server can't compile codeunit references .net assembly

i have variable of type dotnet when trying choose subtype error:

could not load type '' <-- nothing between single quotes!

i've followed steps in msdn guide (save exporting types want use) i've got working locally. can running installing assembly gac, don't want have when should work otherwise

(the add in registered in client add-in table , strong-named correct public key token in table)

these things i've tried:

• building .net 4.5, 4 , 3.5 of worked locally not on server
• dropping dll in client , service add-ins folder
• dropping dll windows/system32 folders
• running administrator (dev environment, service etc etc - i'm logged on domain administrator)
• ripping clumps of own hair out

all assembly calls out webservices , couple of other things, can't work out why can't work

i suspect it's permission related since installing gac seems make happy

any ideas?

thanks in advance

turned out windows server 2008r2 security feature blocks dlls when copied machine

i unblocked , well!