Investors & landlords

I know my cost basis in the stock shares that were merged.  I do not know why 0 was entered as basis. The merging companies: 100% of American Realty Capital Retail Centers of America was merged into American Finance Trust Inc.  For all transactions on the 1099-B column 1a is marked "Merger" except for one which is marked "Cash in Lieu" for a fractional share.  A basis is shown for this fractional share but 0 is shown as the basis for all shares, both "covered" and "noncovered" denoted as "Merger" in column 1a.  Is this sufficient detail or do you need more?