Can't hear solo instrument at all

If i change the first dynamik marking for the flute from "n"??? to "ppp", then it's alright.

The "n" dynamic is set to velocity 49 but with a change of -48 - in other words, it's set to make a sound then immediately pull back to essentially inaudible (49-48 =1, the minimum possible velocity level). The reason you don't hear the crescendo is there is no dynamic after it. It looks like there is a "pp", but that's an illusion, the "pp" is actually attached before the end of the crescendo and then things are manually adjusted to look otherwise. Anyhow, fix that and all is well.

And realistically, you probably should override the default for the "n", as I doubt that's what you actually want. Instead you probably just want it to be velocity = 1, change = 0. I guess there must be some context in which 49/-48 makes sense, but offhand I can't imagine what that might be.

Marc is right, the cescendo is not "visible" with its correct lenght, click on it and type Ctrl + R , you will see. So the first "p" is unuseful, it arrives before the end of the crescendo, so , only the "n" is ....."useful" and so, until the mesure 4 of B, when arrives the first p, and after de "mp" . All what is before is not useful, cause the crecendo-descrescendo are without "nuances" , only the "n" works, and the vélocity -48, make all without sound. I don't know the meaning of "n" I hope my Frenchglish understandable......