I have a line - a street downloaded from OSM. It is in separate parts geometrically, but is contained in one record in the attribute table. That means it is only one row. I would like to split this street into its separate parts (you can see that it is made up of 4 separate lines), but I get this error when I try to run it through Vector > Geometry tools > Singlepart to Multipart. Why is this happening? Why do I need more than one feature to run this tool?