[R] Problem with colors in contour plot

[Loukia Spineli]

Dear R users,

I have a 51 by 51 matrix of p-values (named as pvalue_MA). I want to
present graphically this matrix in a plot (filled contour plot) where both
axes represent probabilities. I have also added a grid in this plot. I want
to highlight in white the cells of the grid that represent p-values smaller
than the (common) significance threshold, 0.05. The code from this plot is
colored in blue (I had to copy-pasted all this code in order to reach to
the plot). I suspect that the "problem" might be in the col parameter of
the filled.contour function. Honestly, I cannot understand why the plot
appears to be completely white!! I checked the values of my variable and it
has a great range from 0 to 1.
Any suggestion/ comment would really help me to move on with my project.

All the best,

Loukia