Did you take the practice tests under full official conditions? (30m each for two essays, 8m break, 75m quant, 8m break, 75m verbal) Did you take the practice tests at the same time of day? Did you have something to eat and drink on the breaks during the real test?
Specifically, did you do the essays (both!) and did you do them with the same attention and brain energy that you did on the practice test?
I see this phenomenon fairly frequently: people mostly ignore the essays because the schools don't care as much about the essays, then they have to do the essays at the start of the official test, and then they're all tired out when the verbal section comes around (normally, they'd be done with the test by now!) and the verbal score drops.
Variations on the above include taking longer breaks on practice tests than are permitted during the official exam, not eating and drinking or eating and drinking too much, OD'ing on caffeine before the official test, taking practice tests at a different time of day than the real test - basically anything that could cause you to be less alert than you should be during the last hour of the test.
Do any of these things ring a bell?
Also, did you take one of our courses? If you did take the course, then you're eligible for a free Post-Exam Assessment. This is a phone call with an instructor to figure out what went wrong and come up with a plan to re-take the test. If this applies to you, please send an email to
studentservices@manhattangmat.com and request the Post-Exam Assessment.