Hi Guys,
I've re-install ACP (without uninstalling the existing files), and the message finally disappear.
Yes, I noticed that there's an option
"Simulated starfield \s and pointing errors (to enable test in daylight)"
which allows me to slew during daytime for testing. and when I unchecked it, ACP refuses to go (since the sun is still above -18 deg from the horizon).
Did a few more test, and it works like a charm.
Thanks for all the tips here.
