Up until recently I've been able to add and subtract values from a given dimension, e.g. a 9" long pipe reduced to 8" by entering "9-1" into the Modify form, by following the standard mathematical functions built into Solidworks. No more.

For some reason, every time I attempt to change a dimension through arithmetic functions I get the error message "Dimension must be between 0 and 30000" (paraphrasing here), and I can't figure it out for the life of me. Everywhere I've looked has no mention of disabling the calculator function or it disabling itself. Does anyone have any insight into this?

Thanks