What? Offering a bonus reduces CTR to merchant site

I'm making some sales for an affiliate site using a 3 page presell with a click to merchant. I even made a slight profit of £20 in February which is encouraging!

However, I am struggling with improving my CTR to merchant

It was about 20% for February (The link is on page 3 where I reveal the name of the product)

So I tried offering a useful bonus to improve this, providing some detailed notes which can help prospects with the product if they buy it. Similar to what Andre Chaperon does on Traffic and Trust

I ask them to e-mail me their name and receipt number (I can't automate this unfortunately as it's not a Clickbank product)

However my CTR has plunged to about 9%.

I understand e-mailing me to get this is bonus is an extra step, but surely people would still click the link to the product to see what's it's about anyway.

Especially if my presell is ok, which I think it is.

Has anyone else experienced this?

What's the best way to start building a list of prospects, ideally of buyers?

I've tested using an SOS, offering a free report, but this didn't work. If they don't buy straight away, they won't buy at all!