Hi Jan,
One sure way to get one's questions answered on the Moodle forums (as on any forum on the Web) is to give a maximum of details and concrete examples of one's problems (as pointed by Dr S Bhatia).
Anyway, here is an example demonstrating how the MCQ-multiple choice answer question type works in Moodle 1.6 (and, I expect, in 1.7).
Question Text: Which if these is an animal? Check one or more answers.
Multiple Choice - Multianswer
Answer 1: the cat
Response 1: Correct. You have found all the animals.
Jump 1: Next page
Answer 2: the dog
Response 2:
Jump 2: Next page
Answer 3: the tulip
Response 3: Wrong. You have either not selected all of the animals or you have selected things which are not animals. Try again.
Jump 3: This page
Answer 4: the crocodile
Response 4:
Jump 4: Next page
Answer 5: the computer
Response 5:
Jump 5: This page
When the program analyses the student's answer, there are only 2 possibilities:
- all of the correct answers AND none of the incorrect ones have been selected
- the student's answer is marked as correct
- the feedback message ("Response") entered for the last expected correct answer in the sequence is displayed
- none of the correct answers OR only some of them have been selected OR all of the correct answers have been selected AND at least one of the incorrect answers has been selected
- the student's answer is marked as wrong
- the feedback message ("Response") entered for the last expected wrong answer in the sequence is displayed
Because only one "wrong answer" Response message and only one "correct answer" Response message are used by the program, you should only enter one of each. If you enter only one of each, it does not matter whether you enter each message for the first or the last (or any other) correct/incorrect expected answer in the sequence.
If you enter more than one Response message for each correct/incorrect case, then you encounter the problem mentioned by you and by Chris in his reply.
Once you understand the system you realize that this is not a bug but "expected behavior" of this question type in the Lesson activity.
Hope that helps,
Joseph