Synchronisation problem

Hello
( and sorry about my english i am french :-)

I have a problem with synchronisation in zoho campaign - to contact.
Evrythink it's ok with 4 synchronisation and it's impossible to have another one.
I juste have information that synchronisation it's "mi en suspens" something like "shelved"
I change how i want to synchronise juste one time not evry day for exemple but nothing change.
I saw a the right that i have 7 synchronisation possible and now i have message that i do 5 synchronisation it's impossible to have more. I don't understand.
Please Help me