Hi everyone,

I'm trying to do a 2-way repeated measures ANOVA with data that looks like
this:
subject block rep  day  light   response
       1     1       1    one    L1      5.5
       2     1       2    one    L1      4.5
       3     1       1    one    L2      4
       4     1       2    one    L2      5.1
       5     2       1    one    L1      5.3
       6     2       2    one    L1      4.8
       7     2       1    one    L2      4.6
       8     2       2    one    L2      4.9
       1     1       1    two    L1      5.2
       2     1       2    two    L1      5.0
       3     1       1    two    L2      3.2
       4     1       2    two    L2      3.4
       5     2       1    two    L1      4.6
       6     2       2    two    L1      4.9
       7     2       1    two    L2      3.3
       8     2       2    two    L2      2.9


I'm using lme():
m1<-light(buoy~light*day, random=~1|subject/day)
summary(m1)

and get this output:
Linear mixed-effects model fit by REML
 Data: NULL
       AIC      BIC    logLik
  24.94574 28.34008 -5.472868

Random effects:
 Formula: ~1 | subject
        (Intercept)
StdDev:  0.05400619

 Formula: ~1 | day %in% subject
                (Intercept)    Residual
StdDev:   0.2912773    0.06415494

Fixed effects: response ~ light * day
                        Value  Std.Error    DF  t-value       p-value
(Intercept)         5.025  0.1515545  6   33.15640   0.0000
lightL2              -0.200  0.2143304  6   -0.93314   0.3868
daytwo             -0.100  0.2109008  6   -0.47416   0.6522
lightL2:daytwo  -1.525  0.2982588  6   -5.11301   0.0022
 Correlation:
                        (Intr)     lghtL2   daytwo
lightL2             -0.707
daytwo             -0.696  0.492
lightL2:daytwo  0.492  -0.696   -0.707

Standardized Within-Group Residuals:
              Min                Q1              Med                Q3
       Max
-0.36863373 -0.15741132  0.03092751  0.14569214  0.32591770

Number of Observations: 16
Number of Groups:
         subject day   %in% subject
                    8                16

My FIRST problem is that I'm not quite sure how to analyse the above output.

My SECOND problem is when I try to use glht(), to get multiple comparisons:
summary(glht(m1,linfct=mcp(day="Tukey")))

I get an error message:
Error in as.vector(x, mode) : invalid 'mode' argument

I"m not sure where this comes from. I've tried everything I (and my
labmates, we are a bunch of field biologists, not statisticians) can think
of, but this keeps coming back.  Is it because glht() isn't appropriate for
2-way ANOVAs?  If that's the problem, what is the correct way to do this?
Or am I going about this completely wrong from the get-go?

Thanks for all the help you can provide!
K

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