hello I have installed a new zimbra 7.1 opensource and when I try to connect a account on zimbra 6.06 I obtain this error:

Code:
Errore:	d2:CN14:MyDomain.it1:O26:Zimbra Collaboration Suite2:OU26:Zimbra Collaboration Suite6:accept4:true5:alias25:MyDomain.it:13026976764:fromi1302697679000e4:host14:MyDomain.it3:icn14:MyDomain.it2:io26:Zimbra Collaboration Suite3:iou26:Zimbra Collaboration Suite3:md532:254DE7B1107FDA410B1C25A238DBAC2B8:mismatch5:false1:s10:13026976764:sha140:36268FEE2F79B25867D66C3B08947D090040B0FB2:toi1334233679000ee
Nota -	Se continui il salvataggio, l'account viene segnato come inattivo.
Premi Annulla per tornare a modificare gli account.
Version is:
Versione 7.1.0_GA_3140.FOSS 29-mar-11


a account external gmail it is connected regularly

Help!