When Locution, Illocution and Perlocution are out of balance, serious miscommunications can occur.
So one day when I drop my iron-wood surfboard on my toe and am loudly lamenting, a Hawaiian lifeguard comes and says, "What's the matter howlee?"
What is he really saying? Is it "What is wrong, you contemptible excuse for a worm;" or "What is wrong my honored and welcomed visitor;" or "What is wrong sir that you are howling so?"
This is the illocutionary consideration.
If I perceive the word "howlee" in its negative sense, then I may complain bitterly to his supervisor that he was disrespectful and perhaps even threatening. This could result in his termination as a lifeguard.
How sad that would be if indeed his intent with the word "howlee" had really been either purely semantic (meaning person who howls) or positive (meaning honored guest).
On the other hand maybe he really had an attitude problem.
NOTES: See a real example of a Pragmatic Disaster.