ACL rights, multiple inheritance from string value

I am trying to make a function that will set ACL permissions, with all the data coming from XML as strings, and I am haven trouble with the Inheritance part. with this code...

$workingPermissions = Get-Acl $target
                $acRights = [System.Security.AccessControl.FileSystemRights]$rights 
                $acInheritanceFlag = [System.Security.AccessControl.InheritanceFlags]::$inheritance
                $acPropagationFlag = [System.Security.AccessControl.PropagationFlags]::$propagation 
                $acType =[System.Security.AccessControl.AccessControlType]::Allow 
                $acUser = New-Object System.Security.Principal.NTAccount($principal) 
                $acEntry = New-Object System.Security.AccessControl.FileSystemAccessRule ($acUser, $acRights, $acInheritanceFlag, $acPropagationFlag, $acType)

everything works fine when only one inheritance flag is used, but when $inheritance = "ContainerInherit,ObjectInherit" it fails. $rights is built the same way, but my understanding is that for whatever reason Inheritance (and Propagation?) don't behave the same way. I found this thread from a few years back, and I am not seeing where the -bor based solution would allow for any string based input. Indeed, I am not understanding it at all, as it seems like $is is just being set to an enumeration, which of course contains both of the enumerations where $flag is set. Anyway, hoping someone can provide the kick my own code needs, and perhaps clue me in on what is really happening in the linked solution too.

Solution

Leave the Propogation flag as None,

Try this one, it works for me

$SAMAccountName = "SamAccountName" ## Type your User/Group SamAccountName
$Rights = "ReadAndExecute"
$InheritanceFlag = @("ContainerInherit","ObjectInherit")
$PropagationFlag = "None"
$AccessType = "Allow"

$NTAccount = [System.Security.Principal.NTAccount]($SAMAccountName)
$IdentityReference = $NTAccount.Translate([System.Security.Principal.SecurityIdentifier])
$AccessRights = [System.Security.AccessControl.FileSystemRights] $Rights
$InheritanceFlags = [System.Security.AccessControl.InheritanceFlags]$InheritanceFlag
$PropagationFlags = [System.Security.AccessControl.PropagationFlags]$PropagationFlag
$Type = [System.Security.AccessControl.AccessControlType]$AccessType
$AccessRule = New-Object System.Security.AccessControl.FileSystemAccessRule($IdentityReference, $AccessRights, $InheritanceFlags,$PropagationFlags,$Type)
$ACL = Get-Acl $Folder
$ACL.AddAccessRule($AccessRule)
Set-Acl -Path $Folder -AclObject $ACL