I enjoyed listening to a teaching from Ps Jim Cymbala on "Obedience in Prayer". I highly recommend you get hold of his video teaching on prayer if you are able to. In any case, he makes the point that sin can cut off the flow of power in prayer. There could be a wide variety of issues that might render your praying useless or put you in a place where you cannot hear the voice of God.
"If I regard iniquity in my heart, the Lord will not hear." (Psalm 66:18). If God is trying to correct us and we are not listening to this correction, we can't make up for it with lots of praying. God will not be moved by our prayers when we are not willing to come into line with His revealed will for our lives.
Regarding iniquity might mean favoring a sin inasmuch as we are not willing to cut it out of our lives.
May the Lord help us to really wait, hear and change in all areas where he is not pleased with our thoughts, words or deeds.
We need to be attentive to our family relationships especially if we want God to be pleased to hear our cries. My attention has been drawn to the passage in 1 Peter 3:7 about husbands dwelling with their wives in an understanding way – or your prayers will be hindered.