I don't know if we can consider this as a bug but parameters in a weblink (used in a webview) are not url encoded and so lead to param errors when passing a string that contains special characters, like "&".
The fix has been added today and will be available in the next nightly build 2.7-rc b350.
If you are using special characters in your GET parameter (whitespace, #, & in your example). Those parameters should be converted according with URL encoding standard, see http://en.wikipedia.org/wiki/Percent-encoding .
Before we passed Field value as it is.
With this fix, if you have '=' sign just before your field (there shouldn't be any white-spaces or other characters) the value from the field will be automatically encoded with URL encoding standard.
For example, if in your Settings->Links->Add web link :