I can't record audio into X3

I confess, I'm a complete newbie at this. All these years I've only used soft-synths and pre-recorded audio in Sonar. I recently bought my first hardware synth. I connected its audio-out to the stereo input on my computer. In my X3 preferences, the stereo input shows as "ASIO4ALL v2 HD Audio Stereo  input 1" for the Recording Timing Master, and "Realtek HD Audio Stereo input" in the ASIO Panel. I inserted an audio track and set "Stereo ASIO4ALL v2 HD Audio Stereo input" as the input. When I arm the track, and press record, and play on the synth, the recording take is dead-silent.
 
I'm using X3 Studio with Windows 8, on an ASUS Pentium i7 gaming laptop with 12 GB RAM.
 
I confirmed that the audio output from the synthesizer works (by plugging it into my headphone amp).
I confirmed that the audio track outputs audio correctly -- by bouncing a synth clip to it, and playing the resulting audio clip.
 
Any suggestions? Thanks!
 
 
 
 
 

LHong
Not sure where problem is, let's start simple one first!
It seems that there is no input audio driver available" for Sonar!
In record devices, set default as "Stereo Mix"!
Good luck!
 

Where do I find "record devices" and set default as "Stereo Mix"?
 
Thanks,
Mike

To hear the synth in real time while you rehearse or record you'll need to enable Input Echo on the audio track. But it sounds like you're saying the recording is a flatline? If that's the case something else is going on as well.
 
There should be a mixer applet for your soundcard in the Windows System Tray. Contrary to what LHong suggested, however, I would recommend you choose "Line In" if it's available. Choosing "Stereo Mix" or "What U Hear" will have you monitoring and recording from the output of the soundcard which can create a feedback loop when input echo is enabled.
 

Did you try LHong's approach in post #4?
 
Another possibility is you need to click on the device after setting it as the default, select Properties, click on the Levels tab, and make sure Level is turned up.