no module named group messaging

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I am installing askbot to existing project with djangobb and djangowiki. Since I am using django1.4 I installed askbot with command pip install askbot==0.7.48 to prevent older non 1.4 compatible version being installed. But now the problem is everything seems to run fine but when I add group_messaging to installed apps, it says no module named group messaging. Why could this be happening? Please help!