The two surfaces you are trying to merge are disconnected from one another. They should overlap, or at least share edges.

public static FailureDefinitionId SiteMergeDisconnected { get; }

Public Shared ReadOnly Property SiteMergeDisconnected As FailureDefinitionId
	Get

public:
static property FailureDefinitionId^ SiteMergeDisconnected {
	FailureDefinitionId^ get ();
}