Drain Design error message ‘drains were affected by this operation’

Symptoms : 
 When designing a drain, you receive an error message: 
 
 Cause : 
 
 Elevation data was collected from low to high elevation where another drain connects. 
 Drain was split with the Split Drain tool. 
 
 
 Solutions : 
 Swap AB before designing so the drain is designed from high to low elevation.