Hi.
After a lot of testing, cleanning , connecting, dissasembling and re assambeling - i found the problem.
as arobatix said, i changed the EI and it fired without any problem.
I opend my malfunctioned EI and found that one of the DC filtering capacitor was broken - i guess its because of the vibration.
i will replace the broken capacitor and hope it will solve the problem.
the capacitor is a 220uF/25V electrolytic capacitor, i will replace it with a 300uF/20V Tantalum capacitor.

thank you all for your help.
Raviv.