You must go through an increased series of ethanol, 80-90-100% , about 10 min each (this depends upon the thickness of your specimen) and then restart with xylene. It should work, however I never checked it
You can dehydrate the sample at 70% EtOH twice(once to rinse off the xylene and then discard off the alcohol and repeat with fresh 70% again) and then to continue your steps to 90% and finally 100%. Then work up your way through following your optimized protocols. This should fix up things.