我自己按DolphinDB的插件教程开发了一个插件，但在loadPlugin时提示：
2020-07-14T02:10:05.505: execution was completed with exception
Couldn't load the dynamic library [/mnt/hgfs/releaseMaster/DolphinDBPlugin/demo/libPluginDemo.so]: /mnt/hgfs/releaseMaster/DolphinDBPlugin/demo/libPluginDemo.so: symbol _ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEED1Ev, version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference
我的编译命令如下：
cd demo
g++ -DLINUX -fPIC -std=c++11 -c src/Demo.cpp -I../include -o Demo.o
g++ -fPIC -shared -o libPluginDemo.so Demo.o -lDolphinDB -L/home/xjqian/database/DolphinDB_Linux64_V1.20.0/server
请问可能是什么原因？
