can a gestational diabetes test b wrong?

Yai
I      I failed my one hour by 3 points
 The first 3 hours test had to b redone because I vomited the glucola. They gave me a pill to take right before I was retested on Wednesday. I kept the drink down by will power alone. My body couldn't handle that much sugar. 
Today I was told that I failed  
Could the results b wrong?
Has something like this happen to any of you?
I can't understand it. I never eat sweets. Only drink water and because of a delicate stomach have a pretty healthy diet. My prepregnancy weight was 98 pounds and I have only gained 12 in 29 weeks. The numbers just don't add up!