[R] factorial anova

[Petra Wallem]

Hello  every body, I am trying to do a factorial anova analysis
following this model:

model<-anova(lm(responsevariable~factorA*factorB))
model<-anova(lm(luz$dosel~luz$estado*luz$Bosque))

 Df Sum Sq Mean Sq F value    Pr(>F)
estado         1 6931.1  6931.1 41.6455 7.974e-06 ***
Bosque         1   36.6    36.6  0.2197    0.6456
estado:Bosque  1   36.6    36.6  0.2197    0.6456
Residuals     16 2662.9   166.4

Strange is that the sum of squares of the factor Bosque are identical to
the SS of the interaction, and are non significant. But when I plot the
data, the interaction surley is significant...

my data.frame looks as follows:

Bosque   estado      lux  dosel
1   deciduo pristino  703 88.56
2   deciduo pristino  800 90.64
3   deciduo pristino  150 95.84
4   deciduo pristino  245 87.52
5   deciduo pristino 1300 91.68
6   deciduo   activo 1900 26.16
7   deciduo   activo  840 59.44
8   deciduo   activo  323 69.84
9   deciduo   activo  112 75.04
10  deciduo   activo 1360 51.12
11 siemprev   activo  900 41.76
12 siemprev   activo  480 65.68
13 siemprev   activo  350 78.16
14 siemprev   activo  350 37.60
15 siemprev   activo  272 58.40
16 siemprev pristino  100 94.80
17 siemprev pristino   60 95.84
18 siemprev pristino   50 97.92
19 siemprev pristino  270 94.80
20 siemprev pristino  110 97.92

Dose some body understand what I am doing wrong??? I have been
navigating at the R site search, but didn't found much posting on
factorial anova.

In advance thanks a lot for your comments
Petra