I'm trying to call getUnitCountForClients method of InfoService service but without any useful result: a) if I ommit clientEmails parameter passing null, request also return null, b) if I specify one or more client email in array request fail with exception "One or more input elements failed validation.". I've tried it on different date periods - doesn't help.

Maybe there are restrictions on account used to connect to API?

I'm using C# in folowing way:

ClientUsageRecord[] aClientUsageRecords = oInfoService.getUnitCountForClients(null, oDT, oDT);

or

ClientUsageRecord[] aClientUsageRecords = oInfoService.getUnitCountForClients(new string[] {"cli...@agency.com"}, oDT, oDT);