One of the common question we have found from the clientexec user regarding blank page appearing while adding a package. This happens due to the php memory limit. You can use the following technique to increase the memory_limit value to 256MB and fix this issue. But you have to make sure the other zend settings are added in the custom php.ini file correctly. The following knowledgebases are handy for this:
http://www.mellowhost.com/billing/knowledgebase.php?action=displayarticle&id=44
http://www.mellowhost.com/billing/knowledgebase.php?action=displayarticle&id=54
If you have any matter of confusion or having any issue, please open a ticket and we will do this for you asap.