Dear Friend
Annual increments in any company will be given to the employees basing on their individual contribution for that particular financial year. Did your company, has linked up increment policy with performance of sales / marketing dept staff or not? If not so, some other reason might be there in your case. Either it may be disciplinary point of view or else your immediate boss may be given wrong feeding about your performance / behavior to higher authorities. It is a common practice in any private organisations. Hence, to know for reasons not giving you annual increment, you should meet HR dept first so that they will inform you about the facts. Accordingly, you can decide to continue in the job or else search for another job
Regards