Tests Fixtures not showing error messages

I’m writing unit and integrations tests for my software. I recently added 5 more tables with foreign keys to my users table. All of a sudden my Users fixture would not fill my test database with values anymore. But there where no error messages whatsoever. It was just complaining about no data in the users table. I couldn’t figure it out, so i added code to the tests, to add the values by hand. After everything was done, i uploaded the code to my git server and then my CI system would fail the build. On that system it complained, that the fixtures couldn’t be added, because a mandatory field was supposed to be filled with a null value.

Why does Cake spit out error messages about the fixture data on the CI system, but not on my development system? PHP errors are turned on on that machine. How can i turn on those errors?