YMLP subscription page code not working properly

Hello,

I'm trying to add the YMLP code to a block (I copy the code from their site as is in the content window), initially it seems to work because it shows the form correctly in the block which is in the right sidebare of my site. The problem shows up when filling in the form and sending it, I have two problems:

1. in the pop-up window I can only see the YMLP page for a split second and then the page I was on when entering the information comes in the pop-up
2. when I replace the target in the submit code of YMLP to _blank I always get an error about not entering a valid e-mail adress even though I enter a working e-mail adress. I have the impression the form-data is not sent to the ymlp servers. Apart from this it opens a second window/tab in my browser with the same page I was on when filling in the form.

What am I doing wrong?

Kind regards

Guy