Esp8266 dev board

I was trying this sketch on my esp8266 development board: http://randomnerdtutorials.com/esp8266-web-server/

When I firstly flashed that board and uploaded the sketch it should've written ip adress, but it didn't and there were no error messages.

Second time I uploaded the sketch, it showed an error. Something like: "only one tcp server allowed"...

I tried to reflashing it several times and still the same. But at least I/O pins work and I can light some LEDs.

Plese help! I don't want my 10$ and my effort to be waisted.