Building relationships in the workplace can sometimes be tricky; however there are some mistakes you might be making in the process that you should try to avoid.

Seeing Relationship Building as Unnecessary and as Playing Office Politics
Some people have a negative perception of the art of building work relationships. They believe that they're above it all and that their knowledge and skills are all they need to excel in the workplace. However, what they fail to understand is that collaboration and large-scale group projects contributes significantly to an organization's success. That's why most organizations are largely 'team-centric'.

Limiting Your Work Circle
Try not to build work relationships with only people in your peer group or people you are similar to. This can be very limiting to you on your career path. Try to develop relationships with people who are not like you - like those in another department, those in different peer groups or those with a skill set different from yours. It doesn't have to be such a deep relationship, but just something cordial and light-hearted enough to secure yourself a place in their conscious mind.

Forgetting the Place of Performance
Avoid using the relationship card to justify laziness and low performance at work. The point of cultivating good relationships is to better accomplish your goals, not to abandon them all together. A good work relationship can't make up for a lack of knowledge or skills, and can hardly protect you from being let go if your work performance is disappointingly low. Good work relationships shouldn't undermine performance.

Making Your Self-Interest Obvious
If in a work relationship, the other person senses you keep doing things because you want something in return, that can end the relationship. Though, self-interest might ultimately be the goal of most work relationships, the point is not to be so blatant with it that it becomes offensive. Keep the needs of the other person in mind and try to give as much as you can with no immediate expectation of return in mind. Make deposits in the person's emotional bank account so you can draw from it during the inevitable rough times.

Being Opportunistic in Your Relationships
Avoid being too status conscious when building work relationships. Try to build good relationships with your subordinates and people you consider to be 'low on the food chain', avoid doing so with only your peers and superiors. Consider the example of a head of department in a business organization, who only got along with his peers and superiors. All his direct reports either feared or genuinely disliked him. The management noticed this and this limited his effectiveness and growth in the organization, because a leader is only as good as the people he's leading.