ggplot2 – R, Name of Scales

I am try to make qqplot with R, but something changed the column name and I can´t figure out what exactly.

This is code :

ggplot(aggMW, aes(x = factor(State, levels = c("silent", "steady", "changing")), 
                  y = NoCorrect, 
                  fill = OnSpeaks)) + 
  geom_bar(stat = "identity", position = "dodge") + 
  facet_grid(Group ~ .) + 
  labs(x = "Condition", y = "Serial recall performance (maximum = 8)") 
  ggtitle("Overall mean number correct per condition") + 
  geom_errorbar(aes(ymin = 0, ymax = 5), 
                width = 0.2, 
                position = position_dodge(width = 0.9)) + 
  scale_x_discrete(c("silent" = "silent", "steady" = "steady", "changing" = "changing"))

and here is the picture of what I am getting.

I just want that the name of the third column will be “silent” and not “NA”.

I tried everything, but it is still NA there