A Raspberry Pi (raspian wheezy) has a cronjob, created as user pi with "sudo crontab -e" so it should has root grants. 

ps aux | grep /home/.../myscript.py

...say it's owner is user "pi"!? (is this correct?)
The python script called from crontab is working fine if i call it from the terminal.
It's reading data from UART (serial port), and save it into a mysql database.
My python script got 'chmod 777' grants.
The crontab file:

@reboot sudo python /home/pi/pythonprogram/myscript.py & > /home/pi/pythonprogram/myscript.log

crontab log file:

Error mysql: 2002 Can't connect to local MYSQL server throught socket '/var/run/mysqld/mysqld.sock' (2)

May it be that my script is called first, before the server (mysql and apache) are running during the boot up process? Is there a way to prevent this?
What else could be the reason for those error?
solved the problem in quite ugly way, but it's working now.
Just added:

time.sleep(5) 

before trying to connect to mysql db.
I would be pleased if someone has a better solution.
Raspberry Pi crontab starts py script at bootup -> logging: error mysql 2002 (can't connect to local server)