Tab Textblock is there, but not visible - Tab1, Tab2, Tab3 etc

Hi everybody,
i created a tab with the preset tool. As in the Tutorials there should be a Tab content… like Tab 1, Tab 2…
This text is missing on my page. Can anyone help? Would be really glad about.

Here is my read only link.

Problem solved. I had no pixelsize in the typography section. Thank you.