No recognition of the timing reference

Hello,
When I start a measurement, REW wait for timing reference and does not recognize it. It does recognize a "timing reference" when the sweep high frequency are playing!
For your information, I use a playback file (the same file I play on the headphones?). The file was previously generated by REW and does incorporate 2 timing reference (one at the begening and one at the end).
Could you please help me please? Than you!

Thank you,
No sorry, I do measure loudspeakers!
The timing references are on the same right channel (before and after the sweep, generated by REW), I clearly hear the timing reference on the loudspeaker (the right one). and while trying to measure the signal level climb to the yellow zone of the small window while the timing reference is playing but no recognition of it. Thank you for your help!

Hello, thank you, it does recognize it now!
The signal does not climb to the yellow zone but to the top of the green. Maybe this is why?
I still have a problem: the measurement is only 5.5s while the sweep is 23 seconds... I will try to solve it alone and do not bother you with this,
Thank you again!

I have V5.20 BETA 44 downloaded this afternoon (in France). The sweep was generated with the same version. Strange.

Yes, I do select "From file" as the playback mode and load the file on the Measure dialog.

I can change the measurement duration manually selecting "from file", browsing the desired file and them selecting "from REW", changing the length to 4M and then going back to "from file" but without browsing again the file. The duration time is then 21.8 seconds...

My beginners questions are of help indeed!
Thank you!
Have a nice day and take care