More information is needed. If they're using a TurboActivate key with the TurboFloat Server, and generating an offline activation request with that then you'll get that error. So, make sure the key is a TurboFloat Server key (edit it to make it that).
Or, if they're not allowed to use that key with the TurboFloat Server, then tell them to use it with the version of your app that uses TurboActivate.