A common response—when you ask somebody for their help or their input—is “I don’t have enough time.” This is an interesting response given that we all have the same amount of time – 24 hours in a day.
When someone doesn’t have enough time it usually means they are focused on something at that moment and don’t want (or feel it’s worth their time) to stop what they’re doing and help you. They don’t have any ‘white space’ at the moment.