I can not connect Demotad to server receiveing error # 10065

Database

I can not connect Demotad to server receiveing error # 10065

I had v2r5 running fine. But recently I got V2R6 from NCR, I removed all files from the add/remove programs and installed V2R6, now I can not able to connect to the host getting error message # 10065. My op sys is win xp.
I would like to know this is problem with old version uninstallation or any thing else.

Thanks in Advance for any body who can solve this problem. I can not test advanced SQL fns. due to this.

Thanks again for help