2001 BMW 330 Starting problem

Electrical problem
2001 BMW 330 6 cyl Two Wheel Drive Automatic 97000k miles

Dear Sir,

Please help me on this mater,

My bmw 330i 2001 some times is not starting when am turning the key ON even the dashboard lights are not coming, only the small digital screen in the dash is getting ON, its starting only after I tray several times to start the engine, or if I kip the key inside the steering box for some time and then it will start normally, when I called up my mechanic he told me to tray moving the gear during the starting to see if it will work or not but It doesnâ?T work, also he told me that it can be the security system of the car,
I think also its not a battery problem because when its starting its starting fin,

Please advice what I have to do I just bout the car and I still not familiar with its services,

Thanks and Regards,

Wessam