To prevent issues like this keep a shareable, group to-do list.
One easy way to do this is with google docs. You can set up a document that outlines each task, who is in charge of that task and the status of the task. Everyone can edit the document with updates on their task.
If you are a fraternity or sorority a great tool to use is WebGreek. WebGreek has a ton of features that make organizing anything super easy. You can share files so you can share a to do list with your brothers or sisters.
There are two awesome group management websites that are super helpful too, Wiggio and Groupspaces. Both of these are awesome tools groups can use to get organized. Both of them help you keep a group on track so nothing slips through the cracks!