Hi,
Sorry but my understanding is tha VB is not supported in MonoDevelop. Some VB stuff can run on Mono if its pre-compiled but in general if you want to work on linux with monodevelop, you are better off switching to C# as the VB story on Mono is not so good.
I do not use Oracle so I do not know how well the oracle ADO.NET libraries work on mono.
Hope it helps,
Joe