connect-mailbox -confir:$false don't work

I'm trying to connect mailbox to some user's and -Confirm:$false don't work.

[PS] C:\Windows\system32>$disable_mailboxes[1]|Connect-Mailbox -LinkedDomainController stb-dc-001.stb.ua -LinkedCredenti
al $b -LinkedMasterAccount ("stb\" + $disable_mailboxes[1].displayname) -Confirm:$false

Confirm
Do you want to connect this mailbox to user "gs.slm/test/testou5/S_user5test" with the alias "S_user5test"?
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"):

$ConfirmPreference = 'none'

$disable_mailboxes[1]|Connect-Mailbox -LinkedDomainController stb-dc-001.stb.ua -LinkedCredential $b -LinkedMasterAccount ("stb\" + $disable_mailboxes[1].displayname) -Confirm:$false

$ConfirmPreference = 'high'

Same problem....

My version: exchange 2010 sp2