Cubase SX1 send effect - Plugin doesn't appear

Hi all,

a customer told me the my Juce-plugin don’t work in Cubase SX1 as a send a effect (no problem in any other host). After some testing i found out that it only appears on the send-effect drop down list in SX1, when canMono() (whats now deprecated in VST2.4) is called. But it seems that the channel configuration (Ins/Outs) then is wrong.
I have no SX1 here installed, so has anyone the same experiences?

Best regards