Powershell: Seemingly valid parameter set doesn't work - powershell

Question

I am putting together a set of tools for internal account management. This particular cmdlet will prep an account for a transfer out, which includes an option to remove or retain their groups. My Param statement has become quite lengthy and has ended up with 6 parameter sets to cover every scenario. All combinations of parameters are working except for one. Here is my code:
function Move-AccountOut {
[CmdletBinding(DefaultParameterSetName='NoTransferHomeDrive')]
Param(
[Parameter(Mandatory=$True, ValueFromPipeline=$True, ValueFromPipelineByPropertyName=$True,Position=1)]
[string]$Username,
[Parameter(ParameterSetName='RetainGroups',Position=2)]
[Parameter(ParameterSetName='RetainGroupsWTran',Position=2)]
[switch]$RetainGroups,
[Parameter(ParameterSetName='RemoveFromAllGroups',Position=2)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran',Position=2)]
[switch]$RemoveFromAllGroups,
[Parameter(ParameterSetName='TransferHomeDrive', Position=3)]
[Parameter(ParameterSetName='RetainGroupsWTran', Position=3)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Position=3)]
[switch]$TransferHomeDrive,
[Parameter(ParameterSetName='TransferHomeDrive', Mandatory=$True, Position=4)]
[Parameter(ParameterSetName='RetainGroupsWTran', Mandatory=$True, Position=4)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Mandatory=$True, Position=4)]
[string]$OldServer,
[Parameter(ParameterSetName='TransferHomeDrive', Mandatory=$True, Position=5)]
[Parameter(ParameterSetName='RetainGroupsWTran', Mandatory=$True, Position=5)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Mandatory=$True, Position=5)]
[string]$NewServer
)
}
Which will generate the following Get-Help output:
Move-AccountOut [-Username] <string> [<CommonParameters>]
Move-AccountOut [-Username] <string> [[-RetainGroups]] [[-TransferHomeDrive]] [-OldServer] <string> [-NewServer] <string> [<CommonParameters>]
Move-AccountOut [-Username] <string> [[-RetainGroups]] [<CommonParameters>]
Move-AccountOut [-Username] <string> [[-RemoveFromAllGroups]] [[-TransferHomeDrive]] [-OldServer] <string> [-NewServer] <string> [<CommonParameters>]
Move-AccountOut [-Username] <string> [[-RemoveFromAllGroups]] [<CommonParameters>]
Move-AccountOut [-Username] <string> [[-TransferHomeDrive]] [-OldServer] <string> [-NewServer] <string> [<CommonParameters>]
The parameter I am having trouble with is the bottom one (transfer only). I can run the command with username, username+retain, username+remove, username+retain+transfer and username+remove+transfer. But transfer without a retain or remove does not work. When run, it throws the following error:
Move-AccountOut : Parameter set cannot be resolved using the specified named parameters.
At line:33 char:1
+ Move-AccountOut -Username X -TransferHomeDrive -OldServer X -NewServer Y
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [Move-AccountOut], ParameterBindingException
+ FullyQualifiedErrorId : AmbiguousParameterSet,Move-AccountOut
I can't figure out why, given that it appears to be a valid parameter set according to my Get-Help output.

Answer 1

Thank you for the output, here is the key (emphasis mine):
Remaining valid parameter set: RetainGroupsWTran
Remaining valid parameter set: RemoveFromAllGroupsWTran
Remaining valid parameter set: TransferHomeDrive
This happens after all parameters have been bound, and it shows that there are 3 valid parameter sets remaining.
TransferHomeDrive is the parameter set you want.
So why are the other ones there?
RetainGroupsWTran should only be possible if -RetainGroups is specified, and RemoveFromAllGroupsWTran should only be possible if -RemoveFromAllGroups is specified.
However, you can also see in the Get-Help output that there is no parameter set where those switches are mandatory, and this is the problem.
Your updated definition looks like the following:
function Move-AccountOut {
[CmdletBinding(DefaultParameterSetName='NoTransferHomeDrive')]
Param(
[Parameter(Mandatory=$True, ValueFromPipeline=$True, ValueFromPipelineByPropertyName=$True,Position=1)]
[string]$Username,
[Parameter(ParameterSetName='RetainGroups',Position=2)]
[Parameter(Mandatory=$true,ParameterSetName='RetainGroupsWTran',Position=2)]
[switch]$RetainGroups,
[Parameter(ParameterSetName='RemoveFromAllGroups',Position=2)]
[Parameter(Mandatory=$true,ParameterSetName='RemoveFromAllGroupsWTran',Position=2)]
[switch]$RemoveFromAllGroups,
[Parameter(ParameterSetName='TransferHomeDrive', Position=3)]
[Parameter(ParameterSetName='RetainGroupsWTran', Position=3)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Position=3)]
[switch]$TransferHomeDrive,
[Parameter(ParameterSetName='TransferHomeDrive', Mandatory=$True, Position=4)]
[Parameter(ParameterSetName='RetainGroupsWTran', Mandatory=$True, Position=4)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Mandatory=$True, Position=4)]
[string]$OldServer,
[Parameter(ParameterSetName='TransferHomeDrive', Mandatory=$True, Position=5)]
[Parameter(ParameterSetName='RetainGroupsWTran', Mandatory=$True, Position=5)]
[Parameter(ParameterSetName='RemoveFromAllGroupsWTran', Mandatory=$True, Position=5)]
[string]$NewServer
)
}
I've made them mandatory within the parameter sets that were showing up in the trace output.
I think that you should also make them mandatory in the RetainGroups and RemoveFromAllGroups parameter sets as well, but it's not shown above.