First, your eggdrop must be ircop to use these feature. Invite seems better, user join if he want.
And which criteria do you want to use to make user coming into target channel ? Everybody ?
If your eggdrop is not on the target channel, it's normal.
You can choose between 2 options:
1. have your eggdrop on #djsohbet and it'll work without error
2. remove the && [lsearch [chanlist $::ctarget] $nick]==-1 part in the condition and your eggdrop will do the sajoin command even if the user is already on the channel.