getSAT(sat.bal, "Fstat") returns NULL

[Rosie23]

getSAT(sat.bal, "Fstat") doesn't return Fstat and return NULL instead

library("pbkrtest")
library("lme4")

  # Data
  data(shoes, package="MASS")
  boy <- rep(1:10, 2)
  boyf<- factor(letters[boy])
  material <- factor(c(rep("A", 10), rep("B", 10)))
  shoe.bal <- data.frame(wear=unlist(shoes), boy=boy, boyf=boyf, material=material)

  # Fit models
  lmm1.bal  <- lmer( wear ~ material + (1|boyf), data=shoe.bal)
  lmm0.bal  <- update(lmm1.bal, .~. - material)

  sat.bal <- SATmodcomp(lmm1.bal, lmm0.bal)

 getSAT(sat.bal, "Fstat") # returns NULL