>Table is open in both datasession.
>
>What I don't understand is that I get the message without any delay, it does not try for 100 seconds as I asked with set reprocess to 100 seconds.

Using the same VFP application session, I can duplicate your observations. However, if I open 2 instances of VFP, reprocess works correctly. I don't know if this is a bug or by design. The following code will reproduce your observations:

oSession = newobject('session')
set datasession to oSession.DataSessionID
set exclusive off
set multilocks on
set reprocess to 10 seconds
use some_table
flock()   && file is locked

set datasession to 1  && default DS
set exclusive off
set multilocks on
set reprocess to 10 seconds
use some_table
? flock()  && FALSE is immediately returned