Why are faces sometimes only displayed in black (in 3ds)?

[a5000]

As can be seen in the picture (right), the faces of standard primitives are always displayed in the assigned color. The left object was created from a spline and the faces are always black. Why ?

Normals are OK and not flipped

[BionicDance]

Have you assigned a material to it, or it is blank like a default object?