Adg699 dishwasher won't start. f2 message
	
	
		Whirlpool ADG699 dishwasher. 
I'm: 
1. trying to start a program (select the program and it's options) and press Start button and afterwards close the cover 
OR 
2. simply press ON button and afterwards close the cover 
RESULT: 
Dishwasher starts to beep (2 times), the led to blink (2 times) and to make a sound and in about 60 secondas stops (the sound stops - and continues beeping and blinking). Opening the cover I can see the F2 message. 
What can I do to make it start? What does the message means? 
Thanks in advance.