FFT size in QT GUI Freq.Sink

[peacockmango lotus]

I was learning about the sampling rate by looking into the tutorial provided in the GNURadio wiki

URL: https://wiki.gnuradio.org/index.php/Sample_Rate_Tutorial

When I was trying to replicate the flowgraph in my 3.8.2.0 version of GNURadio. I got an FFT size error message:

    return _qtgui_swig.freq_sink_f_make(fftsize, wintype, fc, bw, name, nconnections, parent)
RuntimeError: freq_sink: FFT size must be > 16 and < 16384.

Then I tried to increase the FFT size to 17 and then the flowgraph was executed but the flowgraph was not the same as shown in the example.

Attaching the flowgraph for the reference

My question is whether I have built the flowgraph in the wrong manner or is it with the GNURadio 3.8 issue?? 

Regards

Ярослав

Screenshot from 2021-12-31 15-36-43.png
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