The whisper system seems to dislike names with spaces in them, the way to get around this is to put the name in single inverted commas.

So it my name were Mala Fae and you wished to whisper me, then you would send a whisper to "/'Mala Fae' *Insert message here*"

Hope that helps,

Also, the alliance channel doesn't require speakers, perhaps you could try whispering to said person when talking in the alliance channel?

I haven't tested that part, but I believe it works.