How works proxy management?

hi
I'm trying to understand how works the proxy management and fail after many testruns:

my test setup: to test cacheDate of 100.000 URL in Google with 5.000 proxies. Some proxies, max. 20% are always dead, but dead (or just non answering) are always different proxies. It seems to me that STFE never tries a query on more than one proxy: one query sent through one proxy, if proxy dead, the same query will not run through the next available proxy from the list, it gets just NULL, so i get always less results as there are proxies in the list.

Could somebody affirm the same behavior or recommend correct setting to run a query through proxies till it gets an answer?
thx

The GoogleCacheDate isn't proxy enabled. I can look into this for a future release.