Hi Mark,
Thanks for the reply and sorry for the delay! (This is the same message to Jim, above) I had to leave out column headings for 'security' reasons. Column 1 is the sample number (e.g. 76-9). Column 2 is Effect A (e.g. HN) and Column 3 is Effect B (e.g. Control). Effect A has 7 levels, Effect B has 4 levels. There are several response variables in the table. During the initial two-way ANOVA run, I used Column 11 (fourth from the right, e.g. 1.2 at the top). The problem seems to rest with the control level. By the way, there are 10 observations (or tested subsamples) of each replicate; for instance, there are 10 HN x Low x 4 replicates = 40. Ditto with Control.
I hope this makes sense. This is an interactive study where both treatments (A and B) were added to each exp. unit.
Thanks in advance! -LH