When it comes to getting a promotion, it takes more than just hard work.

“Employees generally think they can work hard and do the tasks assigned to them and their promotions will appear. However, that almost never works,” says Nicole Williams, LinkedIn’s career expert.

Experts agree consistent hard work and being a team player are fundamental to career advancement, but office politics, personality traits and other factors also play a role in the promotion decision-making process.

“Sad to say, but employers are not totally objective beings; they have favorites and they hold grudges. It's important for employees to have people at higher levels pulling for them,” says Jim Weinstein, a career coach in Washington, D.C.

Getting passed over for a promotion can be a morale killer. Here are five expert reasons you might have been overlooked for a new title and how to fix them before the next review season:

1. You Lack Leadership Skills  

Not all hard workers make good leaders.  

“Sometimes there are concerns about the employee’s ability to lead and motivate team members and work well with other departments,” says Jenifer Sullivan Grasz, vice president of corporate communications at CareerBuilder.

Management is about knowing when to delegate and when to back off to avoid micromanaging, so be sure to showcase these skills when working on a team project to prove you are ready for more responsibility.

2. You are Disorganized

An untidy desk, messy notes and overbooked calendar can make higher-ups worry you won’t be able to handle more duties.

"Promotions aren’t always about paying one’s dues– they are about proving you are capable of succeeding at the next level,” says Ryan Hunt, corporate communications manager at CareerBuilder.

The quality of your work can often get overlooked if it’s being turned in late.

Missing deadlines is a telltale sign of being disorganized, according to Hunt.

3. You Never Voiced Your Worth

“Your supervisor is most likely busy with their own job and unless you learn to sing your own praises and go above and beyond your assigned duties, that corner office will always be a dream,” says Williams.

There’s a fine line between detailing your achievements and bragging and not looking like a team player.  “Data and numbers speak highly to managers, so use those sorts of metrics to show what you’ve done for your employer,” recommends Scott Dobroski, career expert at Glassdoor.                                                                                                                              

Don’t wait for a promotion to fall into your lap, be a self-starter by taking on new projects that showcase your skill set and pitch new ideas that highlight your worth and commitment to the employer.

4 You Never Told Anyone You Wanted to Advance

“It helps to let your manager know you want a promotion in the first place,” says Hunt. “Even if they can’t consider you for a promotion immediately, it signifies that you are ambitious and ready to take the next step in your career. That attitude can pay off down the line.”

By reminding your boss of your value to the company, you can bridge the gap between your dreams and reality.

“It’s a competitive job market internally and externally, so employees need to be their biggest advocates when asking for a promotion and be ready to prove their value,” advises Dobroski.

5. You Burned too Many Bridges

Interacting cooperatively with co-workers to maintain a productive work environment is crucial to career advancement, and if you are viewed as hard to work with, don’t expect to move up the ladder, experts say.

“It's important for employees to have people at higher levels pulling for them,” says Weinstein.

Not only will being the center of workplace drama have no one rooting for you, but your employer will likely notice the tension you cause and skip your application when looking to promote an employee.  If you have strained any work relations, try mending them by apologizing and seeing things from a different point of view.