WLAN + Notebook + LAN Problem

I got a notebook, one WLAN Router and one computer. If I use my WLAN Card on
the notebook, i can't find my homecomputer, so i can't use the shared
folders. But i can ping the homecomputer or use the remotedesktop to reach
the
homecomputer. If i use my normal LAN on the notebook, i can activate the
client for microsoft networks and all things
work fine. If i use the WLAN i can't use the client for microsoft networks.
If i try to switch it on, it appears a warning, that
the client will be deactivated. Normally it should come a message, that it
will be installed. It is very strange, something is there not right. I need
ideas, what it can be. It is for me very important.
Thanks for each answer

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