String variable in an Active Directory path not working - powershell

Question

I'm writing a PowerShell script to create a new Active Directory group and automatically put it in the correct OU, depending on what department the user is in. The script gets the department from the user in Active Directory and then needs to use that as the name of the OU in active directory. When I don't use the variable in the AD path, this script works.
[string]$department = Get-ADUser -identity johndoe -properties department | Select department
New-ADGroup -Name NewADGroup -GroupScope Global -path “OU=($department),OU=SubDepartment,OU=MainDepartment,DC=OrgName”
However, when I try to use the variable $department as above, I get the following error:
New-ADGroup : The object name has bad syntax
At C:\Users\JohnDoe\Desktop\CreateNewGroup.ps1:7 char:1
+ New-ADGroup -Name NewADGroup -GroupScope Global -path
"OU=($department ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (CN=NewADGroup,DC=OrgName
:String) [New-ADGroup], ADException
+ FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirec
tory.Management.Commands.NewADGroup
How can I call that variable inside the Active Directory path?

Answer 1

You actually have 2 issues here that are common pitfalls.
$department is not a string per se but a string representation of an object with a deparment property. You need to break the string out. That is what -ExpandProperty was for. If you looked at your department now you would see something like #{Department="IT"}
You are also having issues with variable expansion in strings.
[string]$department = Get-ADUser -identity johndoe -properties department | Select -Expandproperty department
New-ADGroup -Name NewADGroup -GroupScope Global -path "OU=$department,OU=SubDepartment,OU=MainDepartment,DC=OrgName"
If you are not calling properties or complex object then removing the brackets is sufficient. Else you can just use a sub expression "OU=$($department),OU=SubDepartment,OU=MainDepartment,DC=OrgName". Without the $ sign the brackets were considered part of the string.

Answer 2

try a dollar sign in front of the opening parenthesis like this:
"OU=$($department)..."