I do not understand, I added the httpS in the paypal link to the site. but nothing happens! Always the same worries.
If what you mean is that you added https in the return URL in your paypal account, this own't work unless your domain and site has an SSL certificate and is configured for https. Even if your site has an SSL certificate and uses https and you have the return URL with just http it will auto convert anyway, therefore you should leave this field without the https.
The email address of the paypal account is not the same as that of Etano, can this cause this error?
It only has to match the email address you entered in the admin "features and options" section for the PayPal payment. It does not need to match your site's email address.
In the admin features and options section for the PayPal payment, double check that the "Payment Data Transfer Identity Token" is correct. If your copying and pasting the token in the field from your PayPal account make sure that there's no spaces at the beginning or end of the token in the field.
I don't know why you're having so much trouble with this, all I can do is make guesses as to what the problem may be because I have no idea what you've actually done. I've known very people that have reported in the forums having this much trouble setting up PayPal and getting it to work. The only ones were those who had "unverified" PayPal accounts and/or were located in countries that PayPal considers high risk which are usually select countries located in the middle east or africa.
As mentioned in this thread:http://forum.datemill.com/index.php?topic=3600.0
If you're making an echeck payment it won't send data because it's not considered an instant payment, it's a pending payment. PayPal uses IPN (Instant Payment Notification) and will only send data if it's a completed instant payment such as by credit or debit card, or by transferring PayPal funds.