Using Beersmith Software/problems with adjustment

In my recipe I have 4 various grains which when added gives me a certain SRM.  When I use the software to adjust the color to lighter or lesser SRM value it recalculates the amount of grains fine.  However, if I want to increase the SRM or darken the beer color after I decreased it it says I need to add more grain, that there is not enough grain to achieve that color.  Shouldn't the software recalculate that for me.  I mean that is the point of using a software program.  For example, I add my grain and achieve an SRM of 7.  Then I adjust color to achieve an SRM of 5.  This works fine.  Then I decide to adjust to a SRM value of 6.  That is when the software won't adjust.  It reports not enough grains instead of just adding the grain amounts to achieve the higher SRM.  Is this a glitch in the software or something else.  Thanks for any help you can provide.

Scott

My understanding of how the color adjustment works is that it fixes the target OG and abv the same and adjusts the ratio when you move the slider. It specifically indicates the possible range it can operate in using the grist bill you start with.

Got an answer from Brad Smith regarding this.  His response was that you need to limit adjustments otherwise you can get some unusual results. His response is found below.

  Its a function of grain color but also volume.  What I do is limit the amount of "adjustment" the program
can do as otherwise it would get very strange results.  For example I could start with a recipe that is mostly
pale malt with a bit of 20L Crystal, and it would go to 100% crystal if I try to adjust the color too much.

  Here's how the color calculation works if you are interested - it is lbs of grains times color divided by volume
in essence that gives you malt color units:
    http://beersmith.com/blog/2008/04/29/beer-color-understanding-srm-lovibond-and-ebc/