We highly recommend you to preview your survey and take it several times to find possible mistakes, especially Logic mistakes.
Click on [Preview] to enter preview mode. The survey you see under preview mode is exactly the same as the one your respondents will see. Go through the survey as a respondent to see if there is any poor question logics.
Data submitted under preview mode won't be saved in database, so try taking it several times to check out all possible mistakes.
Under preview mode: