Is the gain from an installment sale? If so, then the amounts in that section are coming from Form 3805E and the corresponding Asset Entry Worksheet and won't necessarily conform to the "arithmetic" line 28b suggests. Try tracing the amounts back to the AEW.

TTax Terry- I verified that ALL Asset Entry Worksheets show that all such assets are disposed (and the Regular tax and AMT Depreciation Reports show all assets with Code= S  (sold).  So I still contend that Line 28b on CA Schedule D-1 is erroneous. I have to use the Over Ride function to put the proper value on Line 28b (in my case, Line 28a is less than Line 27 so my Line 28b should equal Line 28a).  That Ocer Ride is required to force Sched D-1 Line 28b the be same as federal Form 4797 Line 28b.

@ TTax Terry- I forgot in my response above to state this is NOT an installment sale.