Styx [ tickets ] co-founder Dennis DeYoung is suing his former bandmates for allegedly misusing the group's name and making band decisions without him, according to Associated Press and the Chicago Sun-Times reports.

"This is the most painful decision of my professional career," DeYoung is quoted as saying of the lawsuit in both reports.

In the suit filed on Tuesday (10/10), DeYoung reportedly alleges that he--along with Styx members Tommy Show, James Young, and brothers Chuck and John Panozzo--renewed a partnership contract in 1990 that requires all five of the group's members to agree on any decisions relating to the band and the use of the group's name.

DeYoung's filing of the suit was reportedly prompted by the group's decision to launch a tour without him in 1999. The group is still touring, though Shaw and Young are the only members who signed the agreement in 1990 that are currently traveling with the band; John Panozzo died in 1996, and Chuck is not part of the band's current lineup.

In 1997, DeYoung re-teamed with Styx for a successful reunion tour, but chose to bow out of the group's current road trip. He reportedly claims that he asked the rest of the band to delay the tour, and that the band refused to do so.

"Now they have taken the band's name and excluded me from the decision-making process," DeYoung is quoted as saying in the Sun-Times report. "I have asked for a meeting since July of '98, and the response I've gotten is that there is no interest in talking."

Despite filing the lawsuit, DeYoung reportedly hopes to reconcile with the band.

"I have said from the beginning that reconciliation is absolutely the way to go," he told the Sun-Times. "I'm still hoping that there will be a happy ending to all this."

On Tuesday, Styx manager Charlie Brusco issued the following statement in response to inquiries about the lawsuit: "No one within the Styx organization knows anything about a lawsuit filed by Dennis DeYoung."

The lawsuit reportedly seeks unspecified damages, including profits from Styx's current tour, as well as coverage of DeYoung's costs and attorney's fees.

Styx is currently on tour in Canada, and is set to launch a U.S. tour with R.E.O. Speedwagon next month.