Maybe we need a separate catch-all E-Channel thread?

I've had some trouble since signing up this year, but not sure if still part of the standard operational procedure or not.

1) Signed up a couple of months ago on entry at PEK after immigration.
2) Left PEK some weeks later and E-Channel worked for EXIT, although had some trouble convincing the E-Channel agent that I was 'allowed' to use it, as they kept wanting to send me away to the 'normal' line.
3) Arrived in China again at PKX, and again had trouble convincing the agents that I could use E-Channel. This took some convincing, as they were adamant I was not allowed to use E-Channel. Scanned passport, and was allowed through the first gate. Took fingerprints, and screen showed "approved" or some-such, but the second exit door wouldn't open, and I had to go to the manual immigration after all. Then they took about 30 minutes to scan my passport, inspecting it with a loupe and the likes, presumably as they suspected a forgery...this went on and on, with several officers having a turn, until they realized their scanner was malfunctioning.

They said E-Channel would work on next Entry.

Does this sound right? After signing up, it works on exit but not on re-entry until after a manual entry is processed. Or is it because I signed up at PEK but re-entered at PKX???

And what do you guys/gals do to convince the agents that you're E-Channel eligible???