This is due to a missing image file that is being called for by the part. If this is a standard ArchiCAD part and you are using the default ArchiCAD library (rather than one unpacked and altered in any way), then it is an error with the part and should be reported. If it is a custom part, then the problem is the same, but harder to track down.
Erich
AC 19 6006 & AC 20
Mac OS 10.11.5
15" Retina MacBook Pro 2.6
27" iMac Retina 5K