# Revision history [back]

Have you tried writing Contacts() with upper case, instead of lower case?

contacts = this->parentSensor->Contacts();


Have you tried writing For Gazebo 7+, it should be Contacts() with upper case, instead of lower case?case.

contacts = this->parentSensor->Contacts();


For previous versions:

contacts = this->parentSensor->GetContacts();


Be sure to check the Gazebo version on the tutorial's top-right corner.