Unable to upload program to Arduino

Hi!

I recently bought this Arduino compatible board on eBay to test the nRF24 interface: http://www.ebay.com/itm/UNO-R3-ATmega328P-ATmega16U2-2012-Version-Board-Free-USB-Cable-For-Arduino-/390863072121?pt=AU_B_I_Electrical_Test_Equipment&hash=item5b01412b79

It came with the ATMEGA8A chip, but i replaced it by an ATMEGA328P. When I try to upload the program it gives me the following error: avrdude: stk500_recv(): programmer is not responding. I've tried almost everything, replaced the chip to an official board I have, reinstalled bootloader, installed FTDIUSBSerialDriver, tried all boards in Tools>Boards... but nothing works.

I'll appreciate any clue? Thaks a lot

If it helps, it seems to be the same as this dx.com board: UNO R3 atmega328p avr Development Board for Arduino - Deep Blue - Free shipping - DealExtreme