As CmdrDuh shows, entering the value for INSBASE as a 3dpoint value it works. Why? Well, look at the definition in help:
Type: 3D-point
Saved in: Drawing
Initial value: 0.0000,0.0000,0.0000
Why does entering "0,0,0" work at the command line and not in VBA? Because the command line version does the conversion to a 3d point array for you. When operating with any 3d point in any program language, though, you must be the one to make sure to pass the data in the format it is expected to be.
HTH for any future items of a similar nature....such as when you insert a block using InsertBlock....you wouldn't use "1,1,0" as the insertion point, would you? And just like the initial portion of this thread, you specify a true 2d/3d point to move from/to and not the string version of it.