[Typo3-install] Extensions in TYPO3 Extension Repository Typo3 Ver.4

[Thomas Weber]

I have ugraded 1 TYPO3 System from 3.8 to 4.0 and I´ve installed a new one 
TYPO3 4.o on another Virtual-Server. Every works good.

Only, if I want to install Extension i get the following informations:

If I press the Button "Retrieve/Update" -> The extension list has not 
changed remotely, it has thus not been fetched.

If Itry to find a know extension or retrieve the list of extensions, I get 
the message : -> No matching extensions found.

And this is not possible!

Who knows the problem and a solution?

Thanks Thomas