ST. CHARLES — Missouri casinos have seen an increase in underage gamblers since identification requirements changed as part of Proposition A last fall.

And on Wednesday, the Missouri Gaming Commission made two of the state's biggest casino companies pay for it.

Commission members voted to fine Pinnacle Entertainment Inc. $60,000, for underage violations at its Lumière Place Casino in downtown St. Louis, and Ameristar Casino $25,000, for violations at its facility in Kansas City.

In November, voters approved Proposition A, which ended the state's $500 loss limit and also ended requirements that gamblers sign up for an identification card before entering the gambling floor. Now, casino patrons need only show an ID to a security guard proving they are 21 years old.

But those guards are sometimes distracted, a state investigator told the commission. He reported that six underage patrons had been caught at Ameristar's Kansas City casino this year, all of whom had been at first let in by security.

Michael Winter, executive director of the Missouri Gaming Association, a casino trade group, notes that all of those underage patrons were later caught by casino security. And, he said, through mid-August, there had been just 32 underage violations at Missouri casinos since Proposition A passed, and 19 million patrons.

"We believe we're doing a good job catching people who are under 21 trying to get into our properties," Winter said.

Still, each casino handles ID checks a little differently, and that's a troubling sign, commissioners said.

"We need to move forward on a unified system of checking IDs," said James Mathewson, chairman of the commission. "We've got a problem. And we seem to be addressing it. But we're addressing it in six different directions."

The commission plans to discuss the matter further at its October meeting; In the meantime, members voted to levy the fines.

"That should get the message across. The law is clear," said Gene McNary, the commission's executive director.

The casinos are "the ones who passed Proposition A. They have to make the effort to make sure underage gamblers don't get on."