did you enable admin command before you tried that?
If you did, then you really didn't. Try to TP some where after you enable admin command to check that you have done it right.
You might be typing the char name in wrong or the char isn't there.
Do /pf char name before summoning to see if they're online (and where they are)
That might be /fi to see where they are, not sure. Give it a try