In the userlist tab, it should show the following:
9999:knakworst!sletje@Torn-59392270.upc-i.chello.nl
That will give their whole address the 9999 level. Or, you could use the comand I gave you (preferred method):
/auser -a 9999 knakworst!sletje@Torn-59392270.upc-i.chello.nl
Confirmed with mIRC showing you:
* Added knakworst!sletje@Torn-59392270.upc-i.chello.nl to user list
Once that's done, they should have access to the 9999 join event. Now, if they still can't access the join/part/quit events, there's something wrong outside of what I can help you with on the forums. I'd suggest using named levels:
/auser -a pluss knakworst!sletje@Torn-59392270.upc-i.chello.nl
then changing your events:
on plus:JOIN:#dutch: { ... }
on pluss:PART:#dutch: { ... }
on pluss:QUIT: { ... }