It should come up when you select the PMDG 737 aircaft inside P3D. Sometimes the activation box hides behind the P3D window. If you can't find it try and submit a ticket at http://support.precisionmanuals.com/
I discovered that myself after finally downloading the file late yesterday, now I know the correct answer to this type of problem. Good everything is working for you Yu. :smile:
Can't see anything wrong with your DLL.XML file. Maybe it is the newline characters problem described in this link:
http://support.precisionmanuals.com/kb/a92/dll_xml-information-and-troubleshooting.aspx
Look under "problem 1 - newline characters", try it out and see if it helps. Be sure to back up the file before modifying it.
Windows 8 is not supported by PMDG.
Could you post the content of the dll.xml file?
And you need to sign your post with full name to get support here, it is a forum rule.
You need to read the sticky post, all information is there:
http://forum.avsim.net/topic/464558-13mar15-aerosoft-dvd-and-download-customers-and-fsx-se-compatibility/
And you should sign your post with your full name, it is a forum rule.