If there is no hint of tone on the paper then you need to increase exposure, so the factor should be +9, not -9. That is probably the reason the test strips are still blank. Grades 4 and 5 are usually the ones that cause most trouble because small exposure changes lead to big density changes.
Grade 00 is also troublesome because some papers (including MG IV as you've found) don't produce a really good black at this grade.
When calibrating the exposure corrections you should not change the exposure time after taking a light reading. (The only exception is at grades 4 and 5 if you are not using Ilford filters.) Normally a single reading is sufficient to calibrate all grades - the Analyser will recalculate the required exposure as you change the grade setting. Be sure that the grade settings on the Analyser and enlarger always match, otherwise calibration will fail.
You can take a new light reading for each grade, but there is no need to. Just be sure when you change filtration you change the Analyser's grade setting to match.
Hope that helps!