Are you actually setting it on the tables? Tables are notorious for not inheriting values in 'modern' browsers that they do inherit in IE.
Though really asking for a "Specific" font is nonsense, since Linux and Mac users are unlikely to have that; hence why your font-family should be a stack of fallbacks.
Really without seeing the site or code in question, it's hard to weigh in meaningfully. Could be any of several dozen things interfering... from a specificity error to broken markup.