JetAmerica, the start-up charter airline headquartered in Clearwater, yanked ads for $9 airfares off its Web site Thursday. The reason: the $9 seats were still available only on two flights, both from Toledo to Newark, through September. Spokesman Bryan Glazer confirmed Wednesday that JetAmerica was the subject of an enforcement case by the Department of Transportation. On Thursday, he said the airline wouldn't comment on any "regulatory matters,'' such as whether the DOT balked at JetAmerica advertising $9 fares in big red letters when it was essentially sold out of seats at that price. Last week, the airline canceled its July 13 launch and flights scheduled for the following month. JetAmerica plans to start flying Aug. 14 from Newark to three small Midwest cities and Melbourne in Florida.