[R] Troubleshooting Type III SS and drop1()

[Pamela Wong]

Hi there

I am trying to compute Type III SS plus model selection and find that an error pops up when I'm trying to use the drop1() function with a model output using Anova(). I am looking at effects of four factors and their interactions (with unbalanced sample sizes across some factor groups), on a continuous variable. 

I get an error that reads: "Error in terms.default(object) : no terms component not attribute". I also can't compute an AIC for the model outputs. 

I am wondering if there is something I need to do to my data or if there is some limitation to the analysis I am trying to do.