As you can see on the screenshot all the ressource seems to share the same calendar name ?!
It is not possible to suscribe to a second ressource calendar as they all share the same name.
Here is an ldif file with all the ressources.
The problem is the same with Thunderbird.
Here is the configuration :
-debian 6.0.7
-Sogo 2.0.7-1
version: 1
dn: uid=salle.fourviere,ou=Users,dc=company,dc=tld
objectClass: person
objectClass: organizationalPerson
objectClass: CalendarResource
objectClass: inetOrgPerson
objectClass: top
objectClass: calEntry
cn:: c2FsbGUgZm91cnZpZXJlIChTYWxsZSBkZSByw6l1bmlvbiBkaXJlY3Rpb24p
sn: Salle Fourviere
Kind: thing
mail: salle.fourviere@company.tld
Multiplebookings: 1
physicalDeliveryOfficeName: SIEGE
uid: salle.fourviere
userPassword:: e1NTSEF9WityOVF3cVl3MEhxRUp5Wm9ZK2dnU3l4Z0RJUDlCOTg4MVIraUE9P
Q==
dn: uid=salle.croix-rousse,ou=Users,dc=company,dc=tld
objectClass: person
objectClass: organizationalPerson
objectClass: CalendarResource
objectClass: inetOrgPerson
objectClass: top
objectClass: calEntry
cn:: c2FsbGUgQ3JvaXggUm91c3NlIChTYWxsZSBkZSByw6l1bmlvbiBzZXJ2aWNlIHRlY2huaXF
1ZSk=
sn: Salle croix rousse
Kind: thing
mail: salle.croix-rousse@company.tld
Multiplebookings: 1
physicalDeliveryOfficeName: SIEGE
uid: salle.croix-rousse
userPassword:: e1NTSEF9WityOVF3cVl3MEhxRUp5Wm9ZK2dnU3l4Z0RJUDlCOTg4MVIraUE9P
Q==
dn: uid=salle.tetedor,ou=Users,dc=company,dc=tld
objectClass: person
objectClass: organizationalPerson
objectClass: CalendarResource
objectClass: inetOrgPerson
objectClass: top
objectClass: calEntry
cn:: c2FsbGUgdMOqdGUgZCdvciAoU2FsbGUgZGUgcsOpdW5pb24gY29tcHRhKQ==
sn:: U2FsbGUgdMOqdGUgZCdvcg==
Kind: thing
mail: salle.tetedor@company.tld
Multiplebookings: 1
physicalDeliveryOfficeName: SIEGE
uid: salle.tetedor
userPassword:: e1NTSEF9WityOVF3cVl3MEhxRUp5Wm9ZK2dnU3l4Z0RJUDlCOTg4MVIraUE9P
Q==
dn: uid=salle.bellecour,ou=Users,dc=company,dc=tld
objectClass: person
objectClass: organizationalPerson
objectClass: CalendarResource
objectClass: inetOrgPerson
objectClass: top
objectClass: calEntry
cn: salle bellecour (Salle de reunion services)
sn: Salle bellecour
displayName: Salle bellecour
Kind: thing
mail: salle.bellecour@company.tld
Multiplebookings: 1
physicalDeliveryOfficeName: SIEGE
uid: salle.bellecour
userPassword:: e1NTSEF9WityOVF3cVl3MEhxRUp5Wm9ZK2dnU3l4Z0RJUDlCOTg4MVIraUE9P
Q==
dn: uid=retroprojecteur,ou=Users,dc=company,dc=tld
objectClass: person
objectClass: organizationalPerson
objectClass: CalendarResource
objectClass: inetOrgPerson
objectClass: top
objectClass: calEntry
cn: Retroprojecteur (Siege)
sn: Retroprojecteur
displayName: Retroprojecteur
Kind: thing
mail: retroprojecteur@company.tld
Multiplebookings: 1
physicalDeliveryOfficeName: SIEGE
uid: retroprojecteur
userPassword:: e1NTSEF9WityOVF3cVl3MEhxRUp5Wm9ZK2dnU3l4Z0RJUDlCOTg4MVIraUE9P
Q==
Here is My user Source
{
CNFieldName = cn;
IDFieldName = uid;
MailFieldNames = (
mail,
mailAlternateAddress
);
MultipleBookingsFieldName = Multiplebookings;
UIDFieldName = uid;
baseDN = "ou=users,dc=company,dc=tld";
bindFields = (
mail,
uid
);
canAuthenticate = YES;
displayName = "utilisateurs";
filter = "((objectClass='posixAccount') and (accountStatus='active') and (mail='*')) or ((objectClass='CalendarResource'))";
hostname = ldap;
id = SysocoUsers;
isAddressBook = YES;
kindFieldName = kind;
}, | 
