Arduino yun problem to start a sketch

Hi, i'm new of this forum and i have a problem with the arduino yun board.
I have realized a sketch for this board and starts normally when i connect the board to the PC and open the serial monitor.
I have need of maintain the arduino board without PC, when i connect the board to the power system, the sketch doesn't start automatically (without open the serial monitor). why? how can i solve this problem?

This problem doesen't exist with the arduino uno board.

Could you post your sketch?
Maybe your waiting for some input in the setup method?

I agree with Mamu... maybe you added the code to wait for a serial connection, like the following:

while (!Console){

Ok , thanks the sketch run normally