Calling getCacheStats("QUERY_SERVICE_RESULT_SET_CACHE") produces IllegalArgumentException

Making the following groovy script call using adminshell:

CacheStatistics startCache
try

{ startCache = getCacheStats("QUERY_SERVICE_RESULT_SET_CACHE") }

catch ( Exception e )

{ println( "Exception: " + e.getMessage() ) }

produces this error: Exception: TEIID70013 java.lang.IllegalArgumentException

see attachment for groovy script that was run.