integrating zoho books with crm

When I try to integrate my zoho books with crm etc I get this message "this zoho crm account is already integrated with another organization. so, the integration cannot be enabled."

I have only one organization... so how could that be?

Also when I want to set integration up in zoho books, I read the help file and it instructs me to get the ZSC code and enter it into the "Configure Zoho Books" tab on the Apps and Add ons page, but there is no zoho books when I go there, only zoho projects and so on ( apps I am not using) and none of the apps I am using are on the list!

Thanks before, if you can help.