First, the property name is "lastlogOn", not "lastlogIn".
Second, the value in that propertry is not a PowerShell DateTime object. It requires conversion (like this, assuming $_ represents the AD user object):
$lastLogon = [datetime]::FromFileTime($_.lastLogon)
Third, the lastlogon property is not replicated. It represents the last logon time on THIS domain controller. If you want the most recent logon time you'll have to query each DC and select the most recent value.
Fourth, if you have only a single DC you can avoid the need to convert the value and use the LastLogonDate property instead. Do NOT use this property if you have more than one DC because although it's replicated, the replication interval is a random period between 9 and 14 days -- so you'd still have to look at each DC and select the most recent time.