Sorry Roman, was out of the house tonight.
What Mosfet do you have?
PSMN035?
Middle pin is the drain where the resistors meet up.
The riight hand pin is the Source, which goes to 9V-/ground.
Sounds like you have them swapped.
You are running the sketch I drafted? If so pin 10 is an input with an internal pullup resistor.
You can fake it being a switch by connecting/disconnecting to ground.
Disconnected, it is 'open' and the LEDs shouldbe off.
Connected to ground, it is 'closed' and the LEDs should blink on & off.