Error in ANOVA for model comparison

Hello

I am trying to compare two models using anova(), however I get a message error (see below).
In the net I only found some information on certain library(car) for which one should use anova with A capital letter (Anova instead of anova), but I could not find car library as it says it does not exist.

Model <- lm(interceptG ~ SW + TSC + FSC + PF + SlopeG + K, data=AllTrait)
Model1 <- lm(interceptG ~ SW + TSC + FSC + PF + SlopeG + PHt, data=AllTrait)

Error in anova.lmlist(object, ...) : 
  models were not all fitted to the same size of dataset

I have NA in the datafile, should that be the problem?

Kind regards and thanks in advance
Rosario