First, you should insure SSRS installed and AX2012 installed correctly.

And configure it in AX2012->Sys Admin module->Setup->BI->Reporting services->Reports Server.

1, SSRS services account should have administrator permission (Local server administrator permission)

2, This account also added into AX2012 as a administrator

3, Configure its permission on http://localhost/reports (Open IE as a administrator)

　　--Role center: Content Manager

　　--Site configuration/setting->Security: Make the account is system administrator

When you open report manager but if it reported the error: unable to connect the remote server.

You need add DNS in your hosts file such as IP HostNme

127.0.0.1 localhost

YourIP      YourHostName

3, Insure Remote Registry services is running

4, Run windows powershell as a administrator and follow Microsoft's steps

Set-ExecutionPolicy Unrestricted

/*Confired above as Yes. */

$axmodulename ="Microsoft.Dynamics.AX.Framework.Management"
$axdllname = $axmodulename + ".dll"
$gacfolder = join-path $env:windir "assembly\GAC_MSIL"
$axdll = Get-ChildItem $gacfolder -Recurse -Include *.dll -Name $axdllname
$axdll = join-path $gacfolder $axdll
write-host "Importing AX ManaSalesgement module"
import-module $axdll

Publish-AXReport -ReportName SalesInvoice, SalesAnalysis, SalesConfirm

If no red errors and deployment completed, above AX2012 report shoud be published and you can see them:

http://localhost/Reports/Pages/Folder.aspx?ItemPath=%2fDynamicsAX&ViewMode=List

http://localhost/ReportServer?%2fDynamicsAX&rs:Command=ListChildren 

If you don't publish ax2012 reports, you can't use them in ax2012.

5, when you run reports in AX2012 and reported that init error, pls try to regenerate CIL in check list.