Cannot create new computer in ADSI Edit on an AD L

Using ADSI Edit I cannot use the interface and create a new computer.

Background

So I installed Active Directory Lightweight Directory Services (AD LDS) on my Windows 8.1 Pro computer. Then I followed the tutorial to create an AD LDS instance and then this tutorial setting up groups and users. Everything works as detailed in the those tutorial pages.

However, I want to develop LDAP queries to determine the number of computers in a ActiveDirectory group and so I want to create computer objects. This is not possible from the New menu. I have read elesewhere that the importing of LDIF matters because you need the right schema. So I followed the steps a second time and imported all the LDIF files available which are a subset of the files found (for me) in C:\Windows\ADAM the selection is ...

MS-AdamSyncMetadata.LDF
MS-ADLDS-DisplaySpecifiers.LDF
MS-AZMan.LDF
MS-InetOrgPerson.LDF
MS-MembershipTransitive.LDF
MS-ParentDistname.LDF
MS-ReplValMetadataExt.LDF
MS-SecretAttributeCARs.LDF
MS-SetOwnerBypassQuotaCARs.LDF
MS-User.LDF
MS-UserProxy.LDF
MS-UserProxyFull.LDF

but even after selecting all of those I still cannot create new computer.

Now, it turns out the only ldf files outside C:\Windows\ADAM appear to be SQL Server log data files because the file extension is overloaded.

However, not all the files within C:\Windows\ADAM appear on the list, MS-ADAMSCHEMAW2K8.LDF does not appear. If I poke around in the contents of this file then I can something promising.

...
# Class: computer
dn: cn=Computer,cn=Schema,cn=Configuration,dc=X
changetype: ntdsschemaadd
objectClass: classSchema
governsID: 1.2.840.113556.1.3.30
ldapDisplayName: computer
adminDisplayName: Computer
adminDescription: Computer
# schemaIDGUID: bf967a86-0de6-11d0-a285-00aa003049e2
schemaIDGUID:: hnqWv+YN0BGihQCqADBJ4g==
objectClassCategory: 1
systemFlags: 16
# subclassOf: user
subclassOf: 1.2.840.113556.1.5.9
...

So somehow I cannot select the LDIF file I need. What am I doing wrong?

EDIT: Continuing to Google, it seems I was correct that "By default AD LDS schema does not have a computer class" because this quote appears on this Technet web page.

Experimenting with Extend the AD LDS Schema to Support NFS User Mapping

Using ldifde -i -u -f MS-AdamSchemaW2K8.LDF -s localhost:389 -j . -c "cn=Configuration,dc=X" “#configurationNamingContext” gives the error output below

Connecting to "localhost:389"
Logging in as current user using SSPI
Importing directory from file "MS-AdamSchemaW2K8.LDF"
Loading entries.
Add error on entry starting on line 16: Invalid DN Syntax
The server side error is: 0x208f The object name has bad syntax.
The extended server error is:
0000208F: NameErr: DSID-03100225, problem 2006 (BAD_NAME), data 8350, best match of:
    'cn=Schema,"#configurationNamingContext"'

0 entries modified successfully.
An error has occurred in the program
.

The above problem is solved by the answer here which says do not wrap final term in quotes.

... progressing...and that solved it. will answer my own question.

So extending the schema is the correct thing to do but understand that the instructions at the canonical Technet article have a typo which is corrected at this Technet forum Q & A.

The correct form is

ldifde -i -u -f MS-AdamSchemaW2K8.LDF -s localhost:389 -j . -c "cn=Configuration,dc=X" #configurationNamingContext

Here is proof