"That's not my problem."

"I don't know what to do."

"I'm really upset about this."

These comments reveal something about an employee who is in the 18-34 age group. Millennials tend to focus on their own work production, but being a team player means you have to set aside personal ambitions and life goals to some extent. The concept of "personal mission" is important, but not if it means creating a silo of one. As a leader in business, it's important to look for the red flags that indicate when someone is not cooperating with the team. Here are three of them.

1. You have to do constant follow-ups and reminders

One of the clearest signs is when someone on a team has to be reminded constantly about a task and you have to check in about progress. Why is that a problem? For the employee who is not being proactive, it means there's a lack of understanding about how feeding information and progress to the team helps everyone else. When the person doesn't give updates, it creates yet another silo--and more work for you.

Why this is a Millennial problem: The "what's in it for me" generation doesn't always understand the importance of sharing information to help out the team.

2. You have to set objectives constantly

Team players have one common trait: They tend to ask a lot of questions. Say you just recently hired a graphic designer for your marketing team--someone who works well on the team will ask about which software to use on a project or when to turn in a social media report by asking everyone else. If the new hire is always wondering what to do and seems confused, it's because that person lives in a bubble. You have to set goals for that person because they avoid goal-setting with the rest of the team.

Why this is a Millennial problem: Growing up with pervasive technology makes you insular and somewhat antisocial. Many Millennials don't like asking questions (or talking on the phone). A few will over-focus on personal productivity.

3. You're the one who has to resolve conflict

Conflict resolution is something you do when you want a fellow employee to succeed. Dwelling on conflict is something you do when you only care about your own success. "That person did this to me and I'm upset about it" is bad for team dynamics (and really bad for the company). What works better? "That person is part of my team and resolving this issue will help all of us (and the entire company) succeed."

Why this is a Millennial problem: There's a sense with Millennials that someone else needs to resolve a conflict, that this function is not part of everyone's job description.