Creative Tab doesn't appear

Hello, hello! I'm helping someone make a mod for our SMP, but we're having a bit of trouble: the tab doesn't appear for either of us, even though we did just like the tutorial told us to do. Like, we go to "Add new mod element", we go to Creative Tab and add the tab, putting the icon, enabling it , naming it and then press "Save mod element", but when we test it in our Minecraft test world, the tab simply just doesn't appear to us in creative.