Error when starting PowerBuilder .NET 12.6

PowerBuilder Classic 12.6 a starts without error but PowerBuilder .NET 12.6 fails.

Shown below is a screen snippet showing the error received when starting PowerBuilder .Net 12.6 and the event log for the error.

Also shown below is a screen snippet of the "Control Panel" "Programs and Features" showing Microsoft .NET Framework components installed.

Also shown below is a screen snippet showing that I am running PowerBuilder Version 12.6 Build 3506.

Can anyone help identify how to resolve the error when starting PowerBuilder .NET 12.6? Also, if there is a later build for PowerBuilder 12.6, how can I upgrade to the recommended Build?

Thanks,

Lee Bright