why QuickUsb.openDevice always return false????

I used quick_usb 0.3.1 version,and run on windows,then I did the following and everything worked fine，
1.QuickUsb.init() true,
2.QuickUsb.getDeviceList() success,
3.QuickUsb.hasPermission(_device!) return true,

but when i did QuickUsb.openDevice(_device!), always return flase,Can someone tell me why？？？？？？？