The first set of assessment files submitted were incomplete - However, in view of wanting to see the heat map I had approved 10 out of 15 files that were submitted last week.
In order that the revised files be updated again it was necessary to "Unapprove" (send the approved file back in to the left side folder), by clicking on the X option on the rightmost side.
If we do not do this, the assessor receives a message stating "the file cannot be uploaded as it has already been approved".
Once the file is "unapproved", each assessor is able to upload his revised file and for the manager to receive the updated file. The date of the file apload appears on right side of the table in the "Pending Approval " List as a verification.
The new files need to be approved again as next step.