When I click 'Add Gitolite Repository' from the Admin->Tools->Source page and enter in new info for a repository it fails with the message that the disable_notifications field can not be NULL. My fix for this was to edit the table structure to allow NULL, but you probably want to fix this in your source.
SQL error looks strange! May be module is not activated properly during installation process.
Just try going to activeCollab modules section (your-activecollab.com/admin/modules URL) and click on uninstall button and then install button.
If you face error after that as well, just let us know. We will check it further.
It looks like a possible reason for this error is the ac_gitolite/views/default/ac_gitolite_source/add_source_gitolite_repository.tpl is missing the code for the repository[disable_notifications] field which is set to not allow NULL values, so when the code on line 254 of AcGitoliteSourceController.class.php is run it passes $repository_data which is missing the disabled_notifications fields so when the variables are inserted into the MySQL INSERT statement the last one (disable_notifications) is missing.
Simple fix would be to add it in code or add a field in the form like you have in ac_gitolite/views/default/project_tracking_gitolite/add_git_repo.tpl
{wrap field=name} {label for=repositoryNotification required=false}{lang}Disable Notifications{/lang}{/label}
{lang}Disable notifications every time commits are made on this repository.{/lang}
{/wrap}
Sorry for inconvenience.
I just noticed that some codes are slipped into stable build for notification-management and also FTP-based upload functionality (planned in version 1.5)
This will be rectified in next release due this Thursday.
I apologize again for inconvenience. I hope your gitolite module is in working state as of now.