It happened to me. I was blindsided. I was an AVP with a track record of great accomplishments. My territory consistently performed well and exceeded budgeted gross and net income. I was able to grow the business significantly by adding new product lines and I had a reputation as a supportive and fair manager.

A re-organization in the company resulted in my position reporting to someone new; someone with whom I did not have a relationship and who had a reputation as being difficult. I kept my distance from him. He was part of the “boy’s club” that ran the company.

With the re-organization, a VP position became available. I let him know that I was interested. It was a natural step up given my experience. Many of my direct reports called him to lobby on my behalf. I truly believed that my achievement in the AVP role would land me the job, no question.

But that assumption was a big mistake! The newly appointed SVP had his own agenda for the territory and the business. Because I had no relationship with him, I didn’t know what was involved in the decision making process. What I thought was a shoe-in, ended up being a “blindside”. I did not get the promotion.

High potential women are more confident than ever. Recent studies by Catalyst show that we are getting better about letting others know of our achievements and asking for promotions. But if we continue to avoid the politics, we will continue to set ourselves up to fail.

The workplace is a political environment where decisions about who gets ahead, who gets access to scarce resources and plum assignments are made behind closed doors, doors that are often closed to women. Informal networks, sometimes referred to as the “boys club”, have the power and influence over career decisions. Because women don’t have access to these networks and don’t have access to critical information about how decisions are being made, they risk being blindsided. They simply don’t know the rules of the game.

Click here for the lessons I learned from this experience on Forbes.com.