Upgrade AX4.0/AX2009 to AX2012

Hi All,
I am upgrading from AX 4.0 to AX 2012 R3. I am doing code upgrade checklist. I have completed the step
"Import AOD files into the baseline model store". I am following steps given in the upgradation book and also the link(technet.microsoft.com/.../gg188981.aspx).
When I click on the "Export baseline element ID's " in checklist , it's raise below error :
"The baseline model store contains upgrade preprocessing code. Before you can export element IDs, you must either remove the layer containing the preprocessing code or recreate the baseline model store without it."
Please suggest how to resolved it or which step I have missing.