This probably means the .otf file only contains the basic latin set of the font (i.e. lower and upper case letterforms and punctuation). This is mostly done to reduce the filesize and thus lower the loadingspeed.
In case you want to use the accents, you should look for the extended latin set. On fonts.com when ordering the webfont you can choose between "latin 1(25k)" and "latin ext 1(40k)".
http://www.fonts.com/font/monotype/neo-tech/black/web-font?var=742879