Licence in NW 4.11 Small B.

When trying to install a Connection License with Netware-Admin Tool, after
entereing the Activation-Key I get the following error-Message:
"NLS couldn´t check the activation-password. possible causes: password
entered wrong, wrong activation-password or the checksum of the license is
damaged."
is there a possibility to find out what's wrong? and how can i repair the
corrupt file?
I have installed SP 9.0.

Thanks for support.

Markus