Synology DS1513+ - Install fails without error

Hi
I wanted to use Plex now on my Synology Server but I have a problem.
The basic install is ok and than he ask me to manualy update and this always fails.
I even tried to uninstall it and than install the package manualy from scrap but this didn’t work too.
Any ideas where I can see and find the problem? Is the new version incompatible with other packages?
Thanks in advance

ADDENDUM (as my other post is blocked I reopened a new one):
I didn’t wrote any versions as I thought that it than would be logical that I use the latest versions available:
So DSM is version 6.0.2-8451 Update 1
The automaticaly instalable PLEX version is 0.9.16.3
The version I could download and wanted to install is 1.1.4.2757

Upgrade just write fails (no other message)
Uninstall failed so reboot than uninstall worked (he did install some file of this version as the package version now shows 1.1.4)
Install from scrap (directly version 1.1.4) but writes again failed without any other message
The package seems to install the one or other files as I can access the web interface of PLEX (even after the fail) but no login possible. Even when I want to register a new user he just writes user exists (even if he doesn’t)
Uninstall problematic again (needed to reboot and than uninstall)

Any other infos you need?

Nach einigem hin und her habe ich das Problem gefunden, der Internet Explorer… Mit Chrome hat es jetzt geklappt…
Der Login zuerst nicht da ich da den Login vom Server nahm und nicht von der PLEX Seite…