LPVARIANT parameter problem

Hi list.

I have few days using Jawin in a migration project to java. We have a
problem related with the exception: "org.jawin.COMException: 80070057: The
parameter is not correct." I think that my problem is generated by the
following:

MY METHOD SIGNATURE IN THE .IDL FILE:

[helpstring("method GetDataSet")]
HRESULT GetDataSet( [in] SecurityMode nMode, [in] LPVARIANT lpUserID, [in]
BSTR bstrPassword, [in] UserDataSet nUDS, [in] LPVARIANT lpParams,[out,
retval] LPVARIANT lpDataSet );

...NOW MY INVOCATION OF THAT METHOD FROM JAVA:

invokeN("GetDataSet", new Object[] {new Integer(nMode), lpUserID,
bstrPassword,new Integer(nUDS), lpParams });

The object types of the parameters are the following

lpUserID --> String
lpParams --> CMSPropBag (an own data type)

Is there some problem related to the casting of lpParams to LPVARIANT? if
that is the problem... How should be passed the parameter?

Regards.

Fernando Ocampo