Powershell, Scheduled Task, Exchange

Hello Experts,

I have a somewhat bizarre problem which I cant figure out. I have a windows 2008 server r2, which acts as a script runner. In other words it's only purpose is to run scheduled scripts.
Everything and all of the scripts works fine, except one of the scripts. This script bulks out mailbox end user information from exchange 2003 and outputes it to a csv file.

My problem:
When I run the script manually I get all the headers + information out in the csv file
When the script is run from scheduled tasks, it does not output all the information required.

Script code:
$Date = Get-Date
$Date = $Date.ToString("ddMMyyyy")

Get-WmiObject -Class Exchange_Mailbox -NameSpace root\microsoftexchangev2 -ComputerName ExchangeServerName1,ExchangeServerName2 | where {$_.DateDiscoveredAbsentInDS -eq $null} | select @{Label='SamAccountName';Expression={(Get-QADUser -Identity $_.LegacyDN).SamAccountName}}, @{Label='mail';Expression={(Get-QADUser -includedproperties "mail" -Identity $_.LegacyDN).mail}}, ServerName, StorageGroupName, Storename, Size, mailboxdisplayname | Export-Csv C:\Management\MailboxUserInfo\Exchange2003MUI$date.csv -NoTypeInformation

When i run the script manually heres what the output looks like:
SamAccountName,"mail","ServerName","StorageGroupName","Storename","Size","mailboxdisplayname"
Firma,"Firstname.Lastname@domain.se","SMCR090V","First Storage Group","Std2","184319","FullName"
EM0403,"Firstname.Lastname@domain.se","SMCR090V","First Storage Group","Std2","567","FullName"

But when ran from scheduled tasks, the output looks like this:
SamAccountName,"mail","ServerName","StorageGroupName","Storename","Size","mailboxdisplayname"
,,"SMCR090V","First Storage Group","Std2","184319","Fullname"
,,"SMCR090V","First Storage Group","Std2","567","Fullname"


Conclusion:
As you can see when the script is ran from scheduled tasks it will not output the SamAccountName and Mail... Any ideas experts ?

cheer,s

//Juuso