.net connect to Sybase database,throw exception:Connection to Sybase server has been lost. All active transactions have been rolled back at

Question

After install Sybase v12.54, I tried TableViewer app under samples folder.

But got exception:Connection to Sybase server has been lost. All active transactions have been rolled back.

I added 'Connect Timout=300' to the connection string, it works, but slow...

What's the problem here?

Thanks in advance.