2014 SP5 AddIn won't load...

Good day!

Just upgraded to SolidWorks 2014 SP5 (from 2011 SP0).

Long standing functional VB.NET AddIn won't load... Compiles but won't load in SolidWorks... No errors, just nothing happens, and the AddIn does not come out 'loaded'.

Worked fine when tested on 2014 SP4 a few weeks ago.

I noticed when replacing the SolidWorks references in VS I had to change the .NET Target Version from 2.xxx. I went with .NET 4.0? Good idea, bad idea - I'm not a full time programmer.

Anything else fundamental with the AddIn change, and/or any other ideas why it won't load? The next step is stripping everything out until it works or start fresh with a new template... Hoping there is a better solution.

SolidworksApi macros