This isn't necessarily going to solve your problem but to help get you moving in the right direction......
Logical Predication errors on the GMAT usually refer, generally speaking, to errors of meaning. In other words when it is not logical for one thing to be paired with another. Comparisons in which the things being compared are not logically parallel is an example of this.
So it may be that you are just not really focusing on meaning enough when you read the sentences and are locked in much more to grammar. Grammar issues are of course important but more and more GMAT sentence correction questions seem to be moving more toward logic and meaning and less toward grammar (the trend away from grammar and toward meaning is actually a trend that has been in the works for several years now).
So when you are doing GMAT SC, try to take a step back and think about the sentence logically. Make sure that the implied meaning is both unambiguous and completely logical. If not, it is probably the wrong answer.