When a new dataset finishes processing it may display orange or red warning symbol.
Orange warning symbols are more common and they indicate that some records in your import file could not be processed and have been skipped. To download a file containing just the failed records:
Click the warning symbol
On the Data tab click the menu item on the data row with failed records (three dot symbol)
Select 'Download Failed Records'
The file highlights offending cells and gives reasons why each cell caused the record to be excluded. If you fix up this file it can be 'appended' to your dataset.
Red warning symbols means that something has gone wrong in the processing and no records have been imported. If you see this occur please contact support.