Hi everybody
Finaly the i found the problem, perharps it could serve for other user, read below.
The problem came from the inductive sensor SBA.
In fact the sensor sometimes have no 24v out, just 14.5v, and sometimes 24v.
That's why I didn't think this variation was random.
How i find ...
I see it on SK95 board, the DEL V72 was sometimes less bright than the others.
After i mesure the voltage and i found.
I change the SBA sensor PNP N.O. by an equivalent and the led bright equal the others and ...
Since NO MORE ERROR MESSAGE & IT works