An exclamation icon 
 may be displayed next to the definition of the surface in the Prospector tree view if a source file cannot be located. 
When you attempt to rebuild the surface snapshot, the following error message is displayed: 
Unable to rebuild Surface. Couldn't find file(s).
If you installed Autodesk Civil 3D to a location other than the default, you must update the XML file’s path before you can update the snapshot. 
- To update the path, right-click the surface name in the Prospector tree, right-click, and click Properties. 
 
- In the Surface Properties dialog box, on the Definition tab, click the folder icon next to Import XML File. 
 
- In the Import XML File dialog box, browse to the location of the XML files. 
 
- Click Open. Click OK. 
 
- When prompted if you want to rebuild the surface, click Yes to update the surface properties, and rebuild the surface. 
 
- To update the snapshot, right-click the surface name in the Prospector tree, and click Rebuild Snapshot. 
 
- Right-click the surface name in the Prospector tree, and click Rebuild.