The proxy analyzer works on levels.

The top level, is considered a main engine, the rest are subengines.

Top Levels include:

External Analyzer
Internal Analyzer
KeyPhrase Checking (Define Source Keyphrase checkbox) **** You cannot use a Secondary Level with this
Specific Analyzer ******* Only if this is the only one chosen.  If not, it is a secondary level.

Secondary Levels include:

Specific Analyzer

Third Levels include:

HTTPS Checking

Here is how it works, you choose a top level engine, then a secondary engine (optional), and then a
third level engine.

Ex:

External Analyzer -> Specific Analyzer -> HTTPS Checking

The analyzer will perform all 3 operations on the selected proxies.

You cannot combine keyphrases and an analyzer.

You cannot combine specific analyzer and keyphrases.

You cannot use HTTPS by itself, you need to include it with a secondary engine or primary engine.

You can use the Internal ProxyJudge and a Specific Site Engine (To check 401 against a 3rd party site, not yourself).