Therapy won't help :)
Well I think the answer to your question has been given by others ... you have to create some incentive to make the people WANT to reply. Whether it's ad copy that stirs emotion and elicits a response, an offer they just can't refuse, or some other incentive that makes responding to your message near the top of their priority list. You don't want to disclose what the message is - which is fine - so it's hard for the rest of us to judge your message or service, or give specific ideas. But if repeated attempts are not yielding any results, you know something's got to change. Whether it's the offer, or the product/service all together.
It's a tough market out there - many businesses have to really tighten up the purse strings to make it work - even many who were skating easily before.