Bug in Savage Worlds ruleset

Hm, seems I'm the bugger here ;)

When removing a Bonus from a skill, I get an error message:

add a skill and it's value to a character, like "d6". Then add a bonus to that skill, like "+2". Now the skill value has a darker background. Now try to remove that bonus from the skill - you get an error message.

Anybody noticed that?

Is it when you are a player?
I don't have access to the SW Campaign where I am a player, but I tried it as a GM for the SW Campaign I am running. I was able to add/delete bonuses from Personalities and PCs with no problem.

no, it is when I host a game as GM. Not sure if it happens in player mode...