Some managers expect you to have all the answers, to all the problems. They are disapointed, unhappy that you can't give them what they need and consider it a sign of incompetence.
Their behaviour is a sign of them losing control, of fear, of insecurity. They reassure themselves believing that if they know everything, then everything will be alright. It's a childish behaviour that is very unsettling to see in managers.
The truth is that as long as you have a sound strategy, you don't need to know the details. Don't let anyone tell you otherwise: if you know where you're going, you can make you way a little at a time, tackling whatever gets in the way.
It's like driving at night with the headlights on: you can only see a little aways ahead of you, but you can make the whole journey that way.