No. You must use the correct syntax for the /dde command.
  • dde PLG command "" /aliasname %announce1 %announce2 %announce3
Edit: The /slash is also needed in this case.


And in the mIRC with "PLG" as ddename, an alias to set those vars
alias aliasname {
set %announce1 $1
set %announce2 $2
set %announce3 $3
}