TextView doesn't scroll nor shows scroll bars

I have a Text View embedded in a Scroll View (that's my understanding to get a textView with scrolling ). At the moment I only have enough text in the textView, when I'm running the simulation on a virtual iPhone 6s plus. But although the text window is overfull, it doesn't show scroll bars or starts scrolling.
What am I doing wrong?

Here is a screen shot, if that helps:

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Thanks. Will do so.