Hi,

Could have different reasons.

It can depend on the length of a note.
Let's say in 1 track you have 1 very long note (e.g. a String phrase).
If you click in the middle of the note, you will not hear anything.
(It has to be "generated"/"produced" first.)

But if you have single tones you should normally hear them.
E.g. you click on measure 015:03:0096 and hear nothing, but once 016:01:0000 comes,
you hear the notes.

Another issue could be that the MIDI device doesn't receive any MSB/LSB/PC info.
So it doesn't know what to play.

What happens if you are on the beginning, click play and then move the cursor manually without to stop?
And which device do you use?

Thanks for answering and taking time to help me.

Well, I believe it's the note length. It's a very long single note to work as a background.

As you suggested, I tried to play and then click on the middle of the track and it didn't play too.

Play only if I click play from the very beginning.

I can wait long, but no sound comes.

When you say it's must be "produced", what to you mean ? Rendering it to an audio track ?

As the timeline moves from zero to the song's end, the complete note has to be scanned from its very start to the end in order to be read and create sound.
The midi note contains the octave, note name, pitch, volume, velocity, etc. If you start in the middle of the note the system can't read it from there.

Want more info?
Go here, 2nd paragraph:
https://en.wikipedia.org/wiki/MIDI