How was California State Income Tax withholding calculated

I received a Notice of Tax Return Change from Franchise Tax Board stating that the Tax withholding amount filled was different from their calculation. How do I find out how Turbotax calculated the amount? In the forms filled there isn't any worksheet. There is a significant difference and impacts my refund amount. Could some one let me know how to find that after filling tax. We looked up W2s/1099 and seems FTB's number seems to be correct. We import ADP W2 and 1099 from banks automatically so we shouldn't have human input error. Appreciate your help!