A MTS component in VB should be an ActiveX DLL project, because MTS components by definition can only be ActiveX DLLs (and not EXEs). In order to work with MTS, it is also important to remember that all classes within this ActiveX DLL project must have their Instancing property set to 5-MultiUse, which is the default setting.
Also, MTS requires that Visual Basic components use Apartment threading. So make sure that Apartment Threaded, which is the default, is selected in the Project Properties dialog box.If you want to use the MTS object model, it is required to add a reference to the Microsoft Transaction Server Type Library (mtxas.dll) in the Project References dialog box.