SSHYang,
It's almost always your settings that are causing it to fail. My best advice is to try different times. Most mounts require you to be in a 'window' around the meridian or it won't flip. These are set by your GOTO limits usually. You can test meridian flips during the day. In addition, plate solves around meridian flips often fail if you don't have an adequate delay for settling the mount after a flip. If your stars trail, you can't expect the plate solve to work. Recovery mode won't save you because it is commanding a slew, which requires settling... you can see how that can snow ball.
Without logs and understanding your particular setup, it is very difficult to help you.