We have an application already build in Visual Basic and we just
bought Delphi to enhance it. So, I just wrote a dll with Delphi. My
problem is that everytime I want to access it from Visual Basic, I get
the bad dll calling convention... My function in Delphi is defined as
integer and I pass from vb an integer. when I do the declaration from
VB, I also use integer. Tried it with string type and still does not
work.

Does anybody know if there's sone special rules to follow when
declaring types from Delphi to VB ? Anybody know where I can find a
small sample that would show me how to build a dll for VB.

Have you mentioned the correct form? VB assumes 'by Reference' as
a default, Delphi uses 'by Value' as standard. Therefore
   VB:     Function Test(i As Integer) As Integer
is NOT the same as
   DELPHI: function Test(i:Integer): Integer;

Use either
   VB:     Function Test(byVal i As Integer) As Integer
   DELPHI: function Test(i: Integer): Integer;
or
   VB:     Function Test(byRef i As Integer) As Integer
   DELPHI: function Test(var i: Integer): Integer;

When using Strings:
   VB:     function Test(s As String) As Integer
   DELPHI: function Test(s: pChar): Integer;

In fact

 comp.lang.pascal.delphi.databases     Database aspects of Borland Delphi.
 comp.lang.pascal.delphi.components    Writing components in Borland Delphi.
 comp.lang.pascal.delphi.misc          General issues with Borland Delphi.

   All the best, Timo