To allow http://web5.silverplatter.com/webspirs/start.ws?customer=c5257&databases=S(LO) to be used in a starting point URL, your EZproxy administrator must first authorize the hostname of this URL in the ezproxy.cfg file.
Within this database's section of ezproxy.cfg, the following line must be added:
Host web5.silverplatter.com
The EZproxy server must then be restarted to make the change take effect.