Really stuck with this line:
Start-ADTProcess -FilePath “$($adtSession.DirFiles)\DE Navision\Navision Dynamics 2013 DE\setup.exe” -ArgumentList “/quiet /config "$($adtSession.DirFiles)\DE Navision\Customization file\Navi2013DE.xml”"
Can you see any errors? Have doubble checked files in correct folders.
It’s not working because of the arrangement of double quotes (PowerShell is very particular about placement of multiple double quotes 
)
Your line effectively opens a double quote after -ArgumentList and then closes it after /config , so it doesn’t know what to do with the remaining line
But never fear there is a an answer to this, use the escape character ` (usually found below the Esc key on most Windows Keyboards - not to be confused with a single quote '). Put an escape character infront of each of the extra double quotes, so your line should now read:
Start-ADTProcess -FilePath "$($adtSession.DirFiles)\DE Navision\Navision Dynamics 2013 DE\setup.exe" -ArgumentList "/quiet /config `"$($adtSession.DirFiles)\DE Navision\Customization file\Navi2013DE.xml`""
Thanks for the reply - unfortunately, Im getting the same error.
Error in line 156 (That exact line)
Got it…
Added -IgnoreExitCodes 1,2 
Just for me to learn, can you show the whole line including the new -IgnoreExitCodes 1,2? I’m curious on how that should look.
Start-ADTProcess -FilePath “$($adtSession.DirFiles)\DE Navision\Navision Dynamics 2013 DE\setup.exe” -ArgumentList “/quiet /config "$($adtSession.DirFiles)\DE Navision\Customization file\Navi2013DE.xml”" -IgnoreExitCodes 1,2
Sorry @ruhansen that is not what I explained earlier…
You have missed the PowerShell double quote escaping
It should be (with your new -IgnoreExitCodes 1,2 switch included):
Start-ADTProcess -FilePath "$($adtSession.DirFiles)\DE Navision\Navision Dynamics 2013 DE\setup.exe" -ArgumentList "/quiet /config `"$($adtSession.DirFiles)\DE Navision\Customization file\Navi2013DE.xml`"" -IgnoreExitCodes 1,2