Exchange 2013 Domain Prep Fails: Setup /prepareschema, setup /PrepareAD, Setup /PrepareDomain

Question

Whenever I try to prep for a 2013 exchange install I always get:
"earlier versions of the server roles that are installed were detected"
whenever I try to run Setup /prepareschema OR setup /PrepareAD OR Setup /PrepareDomain
I am working on a Server 2012 standard machine with Exchange 2010 currently installed. This server is a DC (bad I know), DNS, DHCP.
I am trying to prep the domain so that I can install Exchange 2013 on a VM and eventually remove Exchange 2010 from the organization altogether.
There are no other domain controlelrs in the domain. The domain started life as a SBS 2003 machine which was demoted and removed once the server 2012 box was up with exchange 2010 running.
Any help would be greatly appreciated.
Here is some info that may help:
1. PrePare Schema
Navigated an elevated command prompt to the folder with Exchange 2013 CU3.
Ran setup /PrepareSchema
This command should perform the following tasks:
A: Connects to the schema master and imports LDAP Data Interchange Format (LDIF) files to update the schema with 
Exchange 2013 specific attributes. The LDIF files are copied to the Temp directory and then deleted after they are imported 
into the schema.
B: Sets the schema version (ms-Exch-Schema-Verision-Pt) to a Exchange 2013 value.
This command fails with: Earlier versions of server roles that were installed were detected.
First I confirmed that administrator account for domain is a member of schema admins and enterprise admins.
Next I ran asdiedit.
I navigated to: "CN=ms-Exch-Schema-Version-Pt,CN=Schema,CN=Configuration,DC=BDA,DC=LAN"
and reviewed the current "rangeUpper" attribute.
The ms-Exch-Schema-Verision-Pt is not updated to CU3 range Upper setting.
The current range upper 14734 which means its still at Exchange 2010 SP3 settings. 
In short, updaing the schema fails.
2. Prepare Active Directory
Navigated an elevated command prompt to the folder with Exchange 2013 CU3.
setup /PrepareAD [/OrganizationName:<organization name>]
This command fails with: Earlier versions of server roles that were installed were detected.
schema update version 56
I began reviewing the long, long list of the following containers and objects under
 CN=<Organization Name>,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=<root domain>
which are required for Exchange 2013:
missing cn=Auth Configuration
missing CN=ExchangeAssistance
missing CN=Monitoring Settings
missing CN=Monitoring Settings
missing CN=Monitoring Settings
missing CN=Workload Management Settings
Checked Management role groups within the Microsoft Exchange Security Groups OU
missing Compliance Management group  --- Manually created this entry
Step 3 Prepare Domain:
Navigated an elevated command prompt to the folder with Exchange 2013 CU3.
Ran setup /PrepareDomain
This command fails with: Earlier versions of server roles that were installed were detected.
confirmed the following:
ObjectVersion property fails as it is still set to Echange 2010 sp3 -  13040
You have a new global group in the Microsoft Exchange System Objects container called Exchange Install Domain Servers-DONE
The Exchange Install Domain Servers group is a member of the Exchange Servers USG in the root domain.-DONE
On each domain controller in a domain in which you will install Exchange 2013, the Exchange Servers USG has permissions 
on the Domain Controller Security Policy\Local Policies\User Rights Assignment\Manage Auditing and Security Log policy.-DONE
Thanks.

Answer 1

Whenever I try to prep for a 2013 exchange install I always get:
"earlier versions of the server roles that are installed were detected"
Hi,
That tells us that you are trying to run the prep on your combined DC and Exchange 2010 Server - That will not work. Run it on the Server where you plan to install Exchange 2013.
It is not mandatory to run this before the actuall Exchange install - It will run automatically for you, if it hasn't been done already and if you are logged on with an account with the proper permissions.
Martina Miskovic