Powershell creating OU's

$DEPsOUs = @("A","B","C","D")
$createOUs = @('Users', 'Tester')
ForEach ($DEPOU In $DEPsOUs) {
$DEPOUDN = Get-ADOrganizationalUnit -Filter "Name -like '$DEPOU'" | select DistinguishedName | Format-Table -HideTableHeaders | Out-String
#write-host "$DEPOUDN" #checking if output is a string
    ForEach ($createOU IN $createOUs) {
        New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
    }
  }

this is the script, I just created some test OU's inside active directory. the script works but I get some weird issues which I don't understand.

New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Users,
OU=A...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Tester,
OU=...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Users,
OU=B...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Tester,
OU=...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Users,
OU=C...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Tester,
OU=...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Users,
OU=D...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t
 
New-ADOrganizationalUnit : The object name has bad syntax
At line:7 char:9
+         New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (OU=Tester,
OU=...,DC=local
:String) [New-ADOrganizationalUnit], ADException
    + FullyQualifiedErrorId : ActiveDirectoryServer:8335,Microsoft.ActiveDirectory.Management.Commands.NewADOrganizationalUni 
   t

can somebody clarify what is going on ? it creates the OU's with success but this issue appeared.i lauched it in Powershell ISE

I tried a few thing by converting it to string but doesn't really make sense to me when my arrays are string arrays.

You just need to expand the DistinguishedName attribute instead of using Format-Table (meant only for console display) and Out-String:

$DEPsOUs = @("A","B","C","D")
$createOUs = @('Users', 'Tester')
ForEach ($DEPOU In $DEPsOUs) {
    $DEPOUDN = (Get-ADOrganizationalUnit -Filter "Name -eq '$DEPOU'").DistinguishedName
    ForEach ($createOU IN $createOUs) {
        New-ADOrganizationalUnit -Name $createOU -Path $DEPOUDN
    }
}