How do I make a bar graph showing how much space is left?

I understand that the regular bar graph, by default, is supposed to tell me how much space is free on a given drive. Though it says that it is supposed to be the percentage of free space it actually gives the percentage of used space. I would like to make the opposite of what it's doing; a bar graph showing how much space I have left on a drive, or the amount of free space on the drive. I read the help file on status bar graphs and the one on status bar control sequences. It seems that the following expression should give me what I want:

{bgR+f=2,V=pfR,w=50,g=0,c=#a5aa5f,b=#f0f0f0}

However it's not working. Quoting from the help file, "The default is the percentage of free disk space but this can be changed using the V parameter. The and parameters for V can be any of the other status bar codes that represent a numerical value, as well as absolute values. For example, sb/4.7g would display the percentage of selected bytes compared to 4.7 gig - the size of a DVD." For some reason it does not seem to recognize my V value though pfR is supposed to be the percentage of disk space free in the right-hand file display. I get the same if I put in values for dfRa or dfRb and I also tried duRa and duRb. I must be doing something wrong but I can't figure out what it is.

FWIW, I'm using Win7 64bit, 8g memory, Opus 9.5.3.0.3728.x64

The bar graph's V argument needs to specify a value and a total (even if the value is already a percentage) so you just need to specify that it's out of 100.

Instead of V=pfR use V=pfR/100 like this:

{bgR+f=2,V=pfR/100,w=50,g=0,c=#a5aa5f,b=#f0f0f0}

Excellent! That worked perfectly, I appreciate your help!