When Heather Locklear gets sick, her co-workers end up feeling pretty bad too!

Execs on “Melrose Place” had to shell out $600,000 after the TV vixen fell ill and couldn’t make it to work, say sources.

“Producers had arranged to shoot several of Heather’s scenes at expensive locations in the Hollywood area,” a show insider told The ENQUIRER.

“But at the very last moment, Heather’s reps called to say she wasn’t feeling so hot, and wouldn’t be in that day. It threw everyone on the set into an uproar. The producers went nuts!”

The entire shoot had to be rescheduled and revamped as producers moved filming back to a soundstage and ordered several scenes rewritten, according to the insider. A rep for Heather denied that she had missed any work or caused any problems on the set.

But the incident was yet another black mark for Heather, who – as The ENQUIRER recently reported – has been making life hell for the CW series’ cast and crew with her diva antics.

Sources told The ENQUIRER there was tremendous friction between Heather, 48, and now-departed cast member Ashlee Simpson-Wentz.

Heather – who went through alcohol and drug rehab in 2008 – also went ballistic when one of her outfits was missing a button.

Producers hired Heather to reprise her “Melrose” role as diva Amanda Woodward, now a partner in a publicity firm, hoping her star power would give the show’s ailing ratings a much-needed shot in the arm.

But that hasn’t happened, and the CW has reportedly ordered just 18 episodes of the hour-long drama, instead of the standard 22.

“Heather hasn’t picked up the floundering ratings at all, and they’ve had to cut corners to pay her, including letting other people go,” said the insider.

“People on the show say she’s been more trouble than she’s worth, and it didn’t faze her a bit when she cost the show more than a half million bucks after she called in sick at the last moment!”