How to add signing to a project that didn't previously have it?

I have an existing wyp project that has been deployed to various clients. I would like to add signing to my updates without manually deploying a new .wyc file, is this possible?

I tried the following steps but it seems that the public key isn't deployed in the new .wyc file, which makes me assume that it's not enabling signing. Is there a way to enable signing without manually deploying a new .wyc file?

1) - On a test workstation, first install the product using original .wyc file and running wyUpdate. Now I have the latest version. 2) - On the build server, opening my project > File > Properties > Signing > tick 'Sign updates'. Added a new version. Built & uploaded. 3) - On the test workstation, run wyUpdate.exe and let it install the newly built version4) - Inspect the .wyc file on the test workstation, it doesn't appear to include the public key. 5) - Inspect the .wyc file on the build server, it does contain the public key.

To inspect the .wyc file I'm just unzipping it and then viewing the iuclient.iuc file in a text editor. There's lots of binary stuff but items like the URL and current version and the <RSAKeyValue> tag are all readable.

thanks,

Rory