Another professional sports league is in a lockout. The NBA has joined the NFL in a work stoppage after players and owners failed to agree on a new collective bargaining agreement Thursday. The CBA expired at midnight Eastern. The lockout is the NBA's first since the 1998-99 season was shortened to 50 games because of labor strife. Among the issues are disagreements over the salary cap, revenue sharing and guaranteed contracts. The NFL has been in a lockout since its CBA expired in March.