我用ADO组件做多线程数据库查询程序，怎么有时会出现这样的错误‘Connection is busy with results For another command’;

    ThreadOne:=TADODMThreadOne.Create(True,DM.SmartQueryOne);
    ThreadOne.FreeOnTerminate:=true;
    ThreadOne.Resume;    ThreadTwo:=TADODMThreadTwo.Create(True,DM.SmartQueryTwo);
    ThreadTwo.FreeOnTerminate:=true;
    ThreadTwo.Resume;    ThreadThr:=TADODMThreadThr.Create(True,DM.SmartQueryThr);
    ThreadThr.FreeOnTerminate:=true;
    ThreadThr.Resume;    ThreadFour:=TADODMThreadFour.Create(True,DM.SmartQueryFour);
    ThreadFour.FreeOnTerminate:=true;
    ThreadFour.Resume;    ThreadFive:=TADODMThreadFive.Create(True,DM.SmartQueryFive);
    ThreadFive.FreeOnTerminate:=true;
    ThreadFive.Resume;