Failed to Generate Calculation Mesh

Hi,

I have had success with the program and on a current file I am working on I am getting an error of Failed to generate calculation mesh. At this current time I only have three layers and the third layer only has feature elevations with the outline. It appears it is the outline that is causing the issue, but I have not been able to figure out the correction. It shows the orange box in a specific area, but none of the modifications I have made helped with the process of clearing the error.