I activated my survey but some friends/ participants tell me they can`t access it because of an error prompt.

It says
"Internal Server Error

Property "SurveyDynamic.refurl" is not defined.

An internal error occurred while the Web server was processing your request. Please contact the webmaster to report this problem.

Thank you"

Anyone knows how to handle this problem?
It`s frustrating cause those who decide to participate are partly not able to do so..