Missing interaction effect in 2-way anova result

[LauraL]

Hi again.
When i run my aov model (same way i've been running it in other scripts on simelar data), i normally get an output with the interaction effect. Looking like this :

#dataframe from the aov that is working fine

str(omroker1)
'data.frame': 48 obs. of 3 variables:
Snowside : Factor w/ 2 levels "No","Yes": 1 1 1 1 1 1 2 2 2 2 ...
treatment: Factor w/ 4 levels "C_LOG","W_LOG",..: 1 1 1 1 1 1 1 1 1 1 ...
flux : num 1.169 0.978 1.013 0.975 0.921 ...

#Model from my aov that is working fine

model1 <- aov (flux ~ treatment * Snowside, data = omroker1)
summary(model1)
Df Sum Sq Mean Sq F value Pr(>F)
treatment 3 0.1482 0.04941 3.989 0.0141 *
Snowside 1 0.0479 0.04794 3.871 0.0561 .
treatment:Snowside 3 0.0335 0.01118 0.903 0.4483
Residuals 40 0.4954 0.01238
Signif. codes: 0 ‘’ 0.001 ‘’ 0.01 ‘’ 0.05 ‘.’ 0.1 ‘ ’ 1

I run the same code on parts of my new dataframe:

model_dry15_NO3 <- aov (ugNO3.N.g ~ Trt * Snowside, data = dry15.soil_1)

But i only get the effect of Trt

summary (model_dry15_NO3)
Df Sum Sq Mean Sq F value Pr(>F)
Trt 7 0.0583 0.008324 0.516 0.817
Residuals 40 0.6453 0.016133

Problem: i thougt i accounted for the interaction when using * between Trt and snowside?

[technocrat]

Without a FAQ: What's a reproducible example (`reprex`) and how do I do one?, this is hard to answer in the abstract. In the meantime

help(aov

and cut and paste the examples to see if you can map any of them to your situation.