For the next one week, keep a log of all the activities the content you do during every half an hour of your time and analyse. you may notice that you have been interrupted throughout the day by various events. In between interruptions you might have had some time to do what you wanted to do. some interruptions may be functional and related to your job. But most of the interruptions will be non work related. you will notice that you never had major chunk of time and your day was fragmented.
You have to do something to consolidate you time and concentrate on activities which you have to do. There is no point in saying that you did not have the time. The fact is that the available time went to do an activity which is not related to task what you had to accomplish. One way to consolidate you time is to create "unavailable time" which you need to invest on activities which you have to do. An open door policy may be nice to hear. But if you do not know how to implement the same, you will get into problems since your time will be fragmented by various interruptions all through the day.
Use the weekly and daily schedules to your advantage. Make people know when you will be available and when you will not be available. But do it with elegance. Next time when you meet a successful person, notice whether he follows the above principle, you be amazed to find that any successful person knows when to do what work and how much time he should allot for what activity. He will find a way to consolidate his time for major use.