asio drivers not synchronized with the mbox 3 (avid)
therefore it is not possible to sound fl studio
the following table shows:
not enough asio output channels available. at least 2 channels are needed

  I need help please thanks.....

 

It means it FL Studio does not see your interface. If the interface you were using or are trying to use is unplugged, or turned off, or assigned to a task somewhere else, that is the message you will see.

 

theres been more problems with those newer m-boxes then anything! I had to throw mine out only 3months old and repair was over 150 us dollars biggest junk audio interfaces on the market
But I gotta tell you these drivers here are the best ive ever used for all devices see below
UsbAsio Usbasio Drivers Download

The commercial version of the USB Audio ASIO driver supports Alesis' USB mixing desks, ART USB, Audiotrak EX / EX5 / Maya 5.1 USB (48kHz only), Audiotrak EX7 / Maya 7.1 USB, Audiotrak OPTOPlay, Creative Audigy 2 NX (48 kHz only / not on Mac OS X yet), Creative Extigy (48kHz only), Creative MP3+ (48kHz only), Creative SoundBlaster Live 24bit external, Digidesign Mbox, Elektor USB audio, Event EZBus, Edirol UA-1A (44.1kHz only), Edirol UA1-X, Edirol UA-3(D), Griffin iMic, Griffin PowerWave, HHB Portadisc, Hercules MusePocket (48kHz only), I-O Data D2VOX, Lexicon Omega, M-Audio Audiophile USB, Opcode DAT-/SonicPort (optical), Onkyo MSE-U33(HB), Onkyo SE-U55(X(S)), Philips Aurilium (48kHz only), Roland-ED UA-30, Sitecom's 5.1 Audio Adapter (48kHz only), SKNET Digital Sound Station, Terratec Aureon 5.1 USB (48 kHz only), Vivanco 5.1 Audio Converter (48kHz only) and Waveidea UASC-1.

There's some limitations on Extigy: 48 kHz, stereo output, line or mic input (digital input only while output is muted), no MIDI at the moment, no remote control functionality.