We have joomla 3 and plesk. We created the directories for multisites instalation in the folder httdocs/multisites so it would be httdocs/multisites/store1 and so on.
we tried a clean instalation an everything works right.
The problem is when we try a master-slave instalation to share users. Nothing works, the page is blank.
So here are the questions
1.- The main problem should be permissions y plesk?
2.- Is it better for jms plesk or is easy with Cpanel, we can choose the server and if with cpanel is simplier then we hore one of those.
3.- The problem is really in plesk? we have the directories inside the master joomla instalation so it should not be a problem or not?
4.- Our problem is that while in beta we are going to have 1 server and at the en change the server, but if we hire you to fix the problems we should do it twice one on this server and next one on the other?.

Sorry for incovenience but is urgent!!!

Blank page as you can read plenty of time in this forum is generally due to a PHP Fatal error.

1) Yes this can be due to a permission error that can not access a file that would be required.
2) cPanel is far easiest than Plesk
We never encounter any issue with cPanel.
3) If you create a slave site into a subdirectory of your master, this should work on plesk. The most frequent problem with plesk are the different domain or subdomain when the open_basedir is enabled.