If you're wondering why you are not gaining the respect of the people with whom you work... do a quick self-audit to see if you're doing any of these things.
1. Using the word, "try" - it show a lack of commitment and of belief in yourself. Use instead do, act, tackle, accomplish, will.
2. Saying anything the slightly resembles "that's not my job" or throwing a colleague under the bus - protesting anything that isn't in your job description is a surefire way to lose the respect of your leader. And if you want to see the cooperation of your colleagues dry up in record time, point fingers instead of collaborating for a solution.
3. Wearing inappropriate clothing - make sure your clothes fit, are clean, and that you present neatly. Worn old items should be saved for the weekend. If you know you've put on a few extra pounds, don't assume your old clothing fits the new you. And ladies, yes, I'm going there, cleavage is never an appropriate business accessory.
4. Being a gossip. Sadly we didn't leave these people behind in the schoolyard. If gossiping is a form of entertainment that makes you feel powerful, be aware that it makes you look weak and desperate. If you enjoy stirring the pot with rumors and innuendo, it won't do you any favors to be associated with negative news.
These basic respect-killers should be avoided at all costs and could be a core reason why you are not being taken seriously.