ServerName "irc.guihoronan.com": Change this to something other than irc.*. Conventionally the irc.* subdomain is reserved as a DNS Round Robin address. This will not prevent servers from linking provided you don't have an IRCd with the same name and associated link/connect blocks are correct. You do however have your ircd also named "irc.guihoronan.com" according to your log file so you should change your services name.
ServiceUser "*@*": This needs to be a mask, not a wild-carded U@H. For example,
services@myirc.net. This might prevent linking, not sure.
RemoteServer 88.191.133.132 6667 "": You should always use a link password. If you deleted the password for the sake of the paste, please place a dummy password in the field so it doesn't look like you trying to link without a password.
#UserKey1 9866235
#UserKey2 8362013
#UserKey3 2362899: You need these, although optional, they are highly recommended. So highly recommended that they really should be required. Will not stop a link but will cause Services to whine eternally.
Insure that you are using the correct config file. It's very easy to edit one copy, like say on your home computer or your desktop if local but forget to upload/transfer the recently edited copy to services run directory. This can deny a link.