I'm getting the following error when trying to add a pipe between two particular nodes: -

WARNING: Unable to insert element. Make sure the coordinates of the element are not out of bounds. (System.Runtime.InteropServices.COMException (0x80004005): Cannot open database ''. It may not be a database that your application recognizes, or the file may be corrupt.
at ESRI.ArcGIS.Geodatabase.IFeatureCursor.InsertFeatu re(IFeatureBuffer buffer)
at Hnet.Common.Core.CHaMapEditBase.AddGraphElm(String sID, IGeometry pGeometry, IFeatureClass pFeatureClass, Object snType))

Pipes can be added to and from each of these nodes to another node but not between these two nodes in particular.

Any suggestions?