Thanks for the debug information. According to this information, both, the question SD01 and the PHP code are located on page 4.
This won't work, because SoSci Survey will first create the question SD01, then run the PHP-filter (not finding an answer for SD01 so far), and then send this to the respondent. The response to SD01 is not available before page 5.
This is the most common error when creating filters, and easy to solve: Just drag the PHP code to page 5 (at the very beginning of page 5).
To explain the error message: As you have not any answer so far, the function value()
gives you a void result or - as you have re-sent the (non-)answer - the errro code -9:
value("SD01") = -9
None of your IF filters will respond to SD01=-9, because they all expect either 1 or 2, which is fine, as you demand a response. This, in turn, means that the PHP variable $round
will not be set in any of these IF filters. Therefore, SoSci Survey tells you that $round
has not be defined.