Jimmy Page claims Robert Plant's schedule stopped Led Zeppelin touring again.
The group reformed for a one-off show at London's The O2 in 2007, and the guitarist revealed fans were not alone in thinking it would lead to more gigs, but that became an impossibility when it became clear the frontman was too busy working on his 'Raising Sand' LP with Alison Kraus.
Jimmy said: "Some of us thought we would be continuing, that there were going to be more concerts in the not-too-distant-future. Because there was a lot of work being put into the show.
"He was busy. He was doing his Alison Krauss project. I wasn't fully aware it was going to be launched at the same time. So what do you do in a situation like that? I'd been working with the other two guys for the percentage of the rehearsals at the O2. We were connecting well. The weakness was that none of us sang."
Despite their disappointment, Jimmy, John Paul Jones and Jason Bonham continued to rehearse together in 2008, and despite experimenting with guest singers, called a halt to the project because they felt they wouldn't be able to release a record that matched their high standards.
Jimmy added to the new issue of Rolling Stone magazine: "We didn't do any professional recording. We just had a little digital recorder. I thought it was good. I wasn't going to walk away from it. But the weakness came up again. It was, 'We gotta have a singer.'
"It sounded premature [with the guest singers]. I could see what way it was going. Various people thought we should go on tour. I thought we needed a good, credible album, not do something that sounded like we were trying to milk The O2.
"We had put so much toward The O2. And the three of us were catching up with stuff. It was very good, seriously promising. But there was this other thing going on. And that's it."