custom mesh object buildMesh handler

Hi, I have a problem defining a mesh inside a build mesh constructor…
I want to define two custom meshes, with its own specified vertices and face arrays, like mesh1 and mesh2 , and then apply boolean operation with them, and put result in final mesh constructor, like
mesh = mesh1 - mesh2 .
But, i tried defining mesh1 like
mesh1 = mesh vertices:#([0,0,0],[width,0,0],[width,depth,0],[0,depth,0]) faces:#([3,2,1], [1,4,3])
and i get a message Type error: Call needs function or class, got: TriMesh <>
also i tried to create some instance convert it to mesh delete its faces and vertices and add new
on buildMesh do
mesh1 = createInstance box
meshop.deleteFaces mesh1 #{1..mesh1.numfaces} delIsoVerts:true
setmesh mesh1 verts:#([0,0,0],[width,0,0],[width,depth,0],[0,depth,0]) faces:#([3,2,1], [1,4,3])
mesh += mesh1.mesh
i get this error message in setmesh line of code..
MAXScript Scripted Plugin Handler Exception:—Unknown system exception
I really dont know what am i doing wrong or what i’m missing.. Please help