So Why Was Adam Lambert Missing From Last Night's AMERICAN IDOL Finale?

As over 40 former AMERICAN IDOL contestants returned to celebrate the final episode of the long-running singing competition, one alumni was noticeably absent from the festivities - Season 8 runner-up Adam Lambert.

According to Billboard, the singer was not able to appear due to a scheduling conflict with his upcoming appearance in FOX's ROCKY HORROR PICTURE SHOW reboot airing this fall. Lambert was on location filming the musical in which he will play Eddie.

"I know. I'm so sad I missed it," he told Billboard from the Toronto soundstage. "I'll probably go find it online somewhere. It is bittersweet because if I hadn't have been working on this, I would have definitely been there."

Lucky for Lambert, he was able to make a farewell appearance on AMERICAN IDOL back in March when he performed his new single "Welcome to the Show." Check it out below:

About Adam Lambert: International superstar Adam Lambert is a Billboard chart topping, multi-award winning, multi-platinum-selling-singer-songwriter and performer. Best known for his soaring voice and unique blend of theatrical flair and glam-rock sensibilities, the pop singer has performed in front of sold out crowds worldwide -both as a solo artist and with legendary rock group Queen. His work has garnered a number of music awards and nominations including a Grammy nomination for "Best Male Pop Vocal Performance," a BMI Award for "Award-Winning Songs," two GLAAD Awards, a Young Hollywood Award for "Artist of the Year," a Teen Choice Award for "Choice Male Reality/Variety Star," and a People's Choice Award nomination for "Break-Out Musical Artist."

A San Diego, California native, Lambert stepped into the national spotlight in 2009 when he became a finalist on the eighth season of American Idol. His vocal range, along with his unique style, made him a standout contestant and he quickly won over millions of viewers. After the season wrapped, Lambert released his widely successful RCA Records debut, "For Your Entertainment," which sold nearly 2 million copies worldwide to date. The album's first single "Whataya Want From Me," became a radio smash and earned him his first Grammy nomination for "Best Male Pop Vocal Performance." In June of 2010, Lambert embarked on his first headlining tour playing to sold out crowds in the US, Europe and Asia.

His sophomore album, "Trespassing," was released in 2012, garnered rave reviews and became the first #1 debut on the Billboard 200 Album chart by an openly gay artist. Most recently, Adam wrapped a hugely successful world tour fronting Queen, with original band members Brian May and Roger Taylor. Additionally, Lambert had a 5 episode arc on "Glee" during its 2014 season.