custom SMTP Server sink - not firing...

Hello, i'm getting frustrated and i hope someone can help.

i've written a sink, that fires on PostCategorize, but it's not firing...

when i install it in a PC that has another product that uses smtp sinks, it works. on a fresh PC it doesnt...

i've written it in managed sinks:

namespace SMTPSink
{

[Guid("808F4098-82AA-4885-AA21-D772ED1C9E28")]
[ComVisible(true)]
public class SampleInboundSink : IEventIsCacheable, IMailTransportOnPostCategorize
{

void IMailTransportOnPostCategorize.OnMessagePostCategorize(MailMsg pIMailMsg, IMailTransportNotify pINotify, IntPtr pvNotifyContext)

{

  ... code

}

}

I have exchangewrappers.dll which is the wrapper of the interop.

then i did the following:

RegAsm.exe exchangewrappers.dll /codebase

RegAsm.exe microsoft.exchange.transport.eventinterop.dll /codebase

RegAsm.exe mySink.dll /codebase
cscript SMTPReg.Vbs /add 1 OnPostCategorize "mySink" SMTPSink.SampleInboundSink ""
cscript SMTPReg.Vbs /delprop 1 OnPostCategorize "mySink" source Rule
cscript SMTPReg.Vbs /setprop 1 OnPostCategorize "mySink" source Priority 0
iisreset

but it's not fired, and i have no idea what to do more..

like i said, in another computer, that has another product that uses the sinks, its working.

please help?

thanks...