Unable to create Mailbox for newly created users using New QADUser command

I would like to create Exchange Mailbox using powershell script using New-QADUser. In Script, i used few virtual attributes like 'edsva-MsExch-MailboxType'=1;'edsva-MsExch-ApplyEmailAddressPolicy'='TRUE';'edsva-MsExch-ArchiveMailboxEnabled'='FALSE' . I'm able to create the users without mailbox option. 

Please let me know if you need any other information.

Thanks in advance!!