[R] scatter plot coloring problem

[Micha Silver]

Hello:

I have two data frames (subsetted from a larger one). I am plotting 
scatterplots with ggplot2 and coloring by different variables. When 
using one of the variables "Error" with one of the dataframes "conv_df" 
only a single color is displayed. All the other variables show colors as 
expected, and when applying the same ggplot() functions to the second 
dataframe, colors are correctly applied for all variables.

I'm scratching me head over this for some time. Maybe someone can see 
what I'm missing?

My repex is attached

Thanks

-- 
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918