For the first time in its 40-plus-year history, a blackout will keep HBO off the air of one of its biggest distributors.

The signal for the AT&T-owned channel went dark on satcaster Dish and its sister virtual MVPD service Sling TV as of midnight Thursday. Dish alone represents 2.5 million subscribers for HBO.

An HBO spokesman issued a statement shortly after the channel blackout.

“During our forty plus years of operation, HBO has always been able to reach agreement with our valued distributors and our services have never been taken down or made unavailable to subscribers due to an inability to conclude a deal. Unfortunately, DISH is making it extremely difficult, responding to our good faith attempts with unreasonable terms. Past behavior shows that removing services from their customers is becoming all too common a negotiating tactic for them. We hope the situation with DISH changes soon but, in the meantime, our valued customers should take advantage of the other ways to access an HBO subscription so they can continue to enjoy our acclaimed programming.”

Dish had a statement of its own laying blame for the blackout on a move by HBO’s parent company to take a more aggressive stance with its pay-TV partners.

“Plain and simple, the merger created for AT&T immense power over consumers,” said Andy LeCuyer, DISH senior vice president of programming. “It seems AT&T is implementing a new strategy to shut off its recently acquired content from other distributors. This may be the first of many HBO blackouts for consumers across the country. AT&T no longer has incentive to come to an agreement on behalf of consumer choice; instead, it’s been given the power to grab more money or steal away customers.”

While channel blackouts are not a rare sight in the rapidly consolidating multichannel universe–Dish itself has tangled with CBS and Tribune in recent years–HBO has never gotten the ax before. But yanking channels has become an all-too common negotiation tactic as programmers and distributors look for leverage in affiliate agreements.