The CBS College Sports Network has turned down an ad from the National Football League Players Association that presents its side of the dispute over a new contract with the owners association. The "Let Us Play" ad was to have run four times during the cable network's coverage of Saturday's college all-star game. A CBS spokesman said that the network does not accept advocacy advertisements and would not have accepted an ad presenting the owners' side, either. The players association has filed a lawsuit against the NFL challenging an agreement between the league and the television networks in which the networks are required to pay the NFL whether or not a lockout shortens or cancels a season -- an arrangement that the players have described as "lockout insurance." In an interview with Advertising Age, George Atallah, a Players Association executive, said that CBS's rejection of the ad "is clearly indicative of the relationships the networks have with the league."