VB.Net & Delphi

I design all my win 32 API  with Delphi, and use them from VB and C# no problem. 

Just make sure that all is done thru StdCall 

function Distance(Count: integer; X: Double; Y: Double): Double; stdcall; export;

From VB side, just make sure you use the right marshal attributes when needed

<DllImport("MyDelphi.dll", EntryPoint:="Distance", CallingConvention:=CallingConvention.StdCall)>
    Shared Function Distance(Count As Integer, x As Double, y As Double) As double

    End Function