我正在尝试安装Trove-Openstack Juno for Database服务 我在这个文档http://docs.openstack.org/juno/install-guide/install/apt-debian/content/trove-install.html中一步一步地按照，但是我收到了一条错误消息，我不知道如何解决
apt-get install python-trove python-troveclient python-glanceclient \
trove-common trove-api trove-taskmanager
The following packages have unmet dependencies:
python-trove : Depends: python-sqlalchemy (< 0.9) but 0.9.7-1~cloud0 is to be installed
E: Unable to correct problems, you have held broken packages.
请帮帮我！谢谢你们