Hello,
On my schedule, I have a preconstruction main summary and a construction main summary tasks. The preconstruction summary task is starting from project start date and it is fine But, the construction summary task is also starting from project start date, ALTHOUGH none of its sub tasks are starting from project start date. All the tasks under construction phase, are already coming after preconstruction phase tasks, so none of them are starting at project start date. But somehow, the construction summary task is starting from project start date. How can I make the construction phase summary task start from the start date of earliest subtask that it contains?

Unless your summary task is manually scheduled or your calculation mode is set to "manual", the summary task start and finish are determined by the earliest start of any subtask and the latest finish of any subtask.

Take a screen shot and post the picture here (summary task expanded) and we'll try to sort it out.

Julie