Redirection after Paypal standard with multi domains in Drupal

using online membership form.
in using Paypal Standard with Domain Access (multi site) module in Drupal the redirection after using paypal standard is not reverting correctly.
1. after a payment is made via paypal std the user is reverted to the the main site lxx-pxx.info when a payment is being made from another domain site lxx.abc.com.
2. this revertion does not occur when amount is set to zero and no paypal transaction is invoked, confirmation is used, the user that takes out a membership is taken to the correct landing page and url.
3. this is a problem when a the membership is also setting a role type as the user that is obtaining the membership will not be logged in on the incorrect site redirected to.
4. when a role is being set with membership the role will not be activated when the user is redirected to the incorrect website. however this can be rectified later as the membership is still created and payment recorded.
drupal 7.2 on apache and mysql