Why did Las Vegas with Tom Selleck and Josh Duhamel go off the air?

The TV show you're thinking of is actually called "Las Vegas", and while Tom Selleck was a main character, Josh Duhamel wasn't part of the original cast. Duhamel joined the show in its fourth season after Selleck left.

The show was canceled after five seasons due to a combination of factors:

* Declining ratings: While initially successful, the show's viewership gradually decreased throughout its run.

* High production costs: "Las Vegas" was a visually lavish show, featuring elaborate sets, costumes, and special effects, which made it expensive to produce.

* Network changes: NBC, the network that aired the show, underwent some restructuring and changes in programming strategy during the show's run.

Ultimately, the combination of these factors led to the show's cancellation in 2008.