The cost basis on my 1099B differs from what is on the supplemental stock plan lot detail

The cost basis on my 1099B differs from what is on the supplemental stock plan lot detail for stock I sold from an employee stock plan.  My realized gain on my 1099b is $2480.08 but on my Supplemental, I have a realized loss of -$61.37 because on the Supplemental, my Adjusted cost/basis is higher.  How do I account for this?