It looks like you squeezed the entire HTML code for a PayPal button in place of the IMG tag included with one of our buttons, I'm a little surprised that did anything at all.
You need to use our buttons and not PayPal's if you want to use our cart and features, we can still send the buyer/donor to your PayPal account but it has to go through our links for our system to be involved. I would not recommend ever using the button code PayPal provides because they go straight to PayPal and cut us out of the loop.
You can still create an E-junkie button that allows the buyer/donor to enter the amount of their choice. Just go to Seller Admin > View/Edit/Delete Products, select your donation e-book and press Edit.
There you can check the "Let Buyers Edit Price" box and also enter a minimum and/or suggested price that will appear in the shopping cart.
For example if you want buyers to have the option of checking out for free but wish to start them out at 1.00 you can set 1.00 as the suggested price and leave minimum price at 0.00. A buyer would have to intentionally erase the 1.00 price in the shopping cart to check out free.
Once you have made those changes be sure to submit them and get the updated button code we provide at the end of the process. It will still look like a regular Add to Cart button but it will send your buyer to checkout at PayPal with the amount they wish to donate.
If you want to change the image used for the button just replace the part that says http://www.e-junkie.com/ej/ejadd_to_cart.gif with the URL of a different image file, something like http://www.paypal.com/enUS/i/btn/x-click-but04.gif rather than more HTML code.