Can't get FFT of Sample & Hold sinusoidal wave in Simulink
I'm no Simulink expert, but I'm pretty sure you don't want sample and hold, but just sample as functionality: As far as I can guess, sample and hold doesn't convert from simulatedly continuous signal to simulatedly discrete signal, but just actually does what its name says, and probably generates a continuous signal, not a discrete one.

In fact, seeing that you're already using a DSP sine, I'd say: instead of using a separate block with a trigger, just change that DSP Sine's sampling rate.