Oh my. Mistakes galore.
first of all, you need to call Parent::onClientEnterGame(%this); at the end there.
Secondly, what's the point of doing findClientByBL_ID when you have %this representing the client right there?
Also, considering you wanted it to be only people from a list, you would use if(bla bla bla) then within that if statement, set the clan tags.
And, you seem to be calling clansuffix as a function. It's a variable, so you can take out the brackers, and throw in an equals sign. (like Deep mentioned)
Why are you setting suffix twice? Don't you want prefix and suffix?
And lastly, you seem to be setting [BW][Hoster][Fighter][Ace Pilot][Recruiter] and [BW][Fighter][Ace Pilot][Recruiter] to the same person.