Why didn't the Jews understand "Eli, Eli, lama sabachthani"?

> And about the ninth hour Jesus cried out with a loud voice, saying, "Eli, Eli, lama sabachthani?" that is, "My God, My God, why have You forsaken Me?" > > Some of those who stood there, when they heard that, said, "This Man is calling for Elijah!" (Matthew 27:46-47, NKJV) According to a number of sites, including Wikipedia , the saying "Eli, Eli, lama sabachthani" (or in Mark's version "Eloi, Eloi, lama sabachthani") was originally Aramaic: > אלהי אלהי למא שבקתני. > > Courtesy of Wikipedia However, according to some other sites it is Hebrew. Regardless of which is right, I don't think it can be denied that the Jews mistook what he said. I used to take this to mean that he was speaking in a language they did not understand. However, as far as I know and have learned from our good friend Google, Jews at that time spoke both Hebrew and Aramaic (plus some Greek, and perhaps Latin). How, then, did the Jews mistake his meaning?