Hi Dick,
If you get an error on "USING VO", then you have not added any of the standard VOSDK libraries as references. Or you have accidentally added the new X# strongly typed versions of those dlls instead (for those, you would have to use "USING XSharp.VO.SDK").
The reason is that the name of the class in X# is not called anymore "DBserver", but it is now named "VO.DBServer" for the standard VO GUI classes and "XSharp.VO.SDK.DBServer" for the new fully strongly typed classes (still under development).
The reason for this rename, is that we do not work anymore in the small VO environment, but we have to play well with 100s or 1000s other .Net languages and libraries, where it is very easy to have naming conflicts. If you search in the web, you will find plenty classes named DBServer already, so there must be a way to distinguish each from another.
The solution in .Net (and other environments) is to use larger, more descriptive class names and for example the main system window class is named "System.Windows.Forms.Form", the 64bit integer type is named "System.Int64", and following the same patter, the VO-compatible class for managing dbfs is named "VO.DBServer", while the strongly typed version is named "XSharp.VO.SDK.DBServer". You can find other similar named classes by other .Net developers, like "Teco.DBServer", "Oci.DatabaseService.Models.DBServer" and many more, which of course have nothing to do with "our" DBServer. If everybody was just using instead simply "DBServer" for their class names, we would end up having conflicts impossible to resolve. The dots inside the names are used by convention, class names could have also been named simply "SystemWindowsFormsForm" or "VODBServer", but
using the dots inside the names makes them more readable.
So that's the reason why you need to use "VO.DBServer". But, because it is tiresome to write "System.Windows.Forms.Form" or "VO.DBServer" etc all the time, the .Net compilers offer a "shortcut", they let you specify the first part of the class name (which is by convention called the "namespace" part) in a USING statement, and then you can address the type simply by the last part of its name. X# goes one step further, it provides a compiler option to tell the compiler to automatically add (transparently to the programmer) such USING statements, when using libraries compiled in X# (such like the X# versions of the VOSDK), to make things even easier. So that's why you need to either enable that project option, or provide the necessary USING VO statements manually.
.