求解：法铁官网购买图尔-里昂车票，出现警示信

买图尔到里昂的票，60岁以上老年人，选择价格后上方显示红色警示：
！On some trains, the place you requested isn't available for the fare you chose. We have reserved you a place with different criteria instead.
Attention, some of your requests for seats cannot be satisfied.
求解：什么意思呀？这票能买吗？警示下方倒是4个步骤都显示，填写乘客信息、购票人信息、打勾等，操作后没有反应。