I haven't tried it because I'm at work, but you should try to say... "send a text message to 'blahblah'.." Siri should ask what you want the text to say, then you respond "When is the meeting scheduled for?"... that should probably work.
Siri thought I wanted to text my wife and some person named "some" because in this particular context there were two recipients as Siri interpreted the first word of my message ("And") as a logical AND operator.
"Tell" is a shortcut for the longer form of sending a text which avoids this predicament:
Send a message to my wife saying And get some beer