I added the following line:
$tgthost.Backing.PnicSpec[$_].UplinkPortGroupKey = $UplinkKey
I used the PortGroup key i find here for the port group of the DATA-UPLINK that the pNICs should be connected to
Get-VirtualSwitch -Distributed | Get-VirtualPortGroup
I use the port group key... not the port key.
Each port group has a unique key. So lets say i want to connect both pNICs to DATA-UPLINK and DATA-UPLINK has a portgroup key of "dvportgroup-149"
That's what I specify in my $uplinkkey variable.
Make sense?