That's good. Sorry I jumped to that conclusion. Had a few users trying to install on J1.6 lately, and that's the error they're getting.
The next thing to try is a manual installation. To do this, you'd unzip the entire contents of the JFBConnect package (or FTP) to a directory in your sites temp folder like c:\Inetpub\wwwroot\joomla\tmp\jfbconnect
Then, in the Joomla Installer manager, use the Install From Directory option and give that same directory folder. This bypasses the uploading and uzipping issues which, unfortunately, happen on some server configurations.
The only thing confusing from what you pasted above is the very end of the line: netpub\wwwroot/.. Not sure if that was an accident or not, but the last slash is a forward slash, which is more for Linux. If you can paste the whole error line you're getting, that may help further narrow down the issue if the above doesn't help.
Keep us posted, and good luck!