Hi Santos,
The signal should (and most probably is) being streamed out from the source block as you set it up. The update period of the number sink is only to tell it when to look for a new value and retrieve it to the label. It is just a visualization tool. So you'll see that, by setting your update period to something significantly smaller than the period of your signal, you get a faster response in exchange of higher computational effort. But setting it with the same period of your signal means that you'd fetch one value of it at the number sink once per period.
As it is just a visualization tool, it wont affect the functionality of your implementation. You can (and have already, according to your first email) prove this by comparing the output of the number sink with a time sink. You said that you saw the signal in the time sink as you expected, which is great, and also tells you that you set up the signal source according with your expected behaviour.
I hope I clarified a bit your inquiry.