It SEEMS to be saying that column A of the 1040-X is not what was on the previous 1040 or 1040-X (before the current amendment). Column A must be what was shown on the previous return ie before the current amendment. Did you save a PDF of the previous return so you can check? if not you'll have to wait until the transcript of the last accepted return posts to your account.
you should wait to see what others say because this error message does not show upin a web search.