is it a bug or problem in setting in render in archicad 15

[Anonymous]

hello everyone while i am rendering in archicad 15 during the process of the render i face these black on the walls and floors but after end of processing it dissappears it was not like that in previous versions of archicad is it a problem in my setting or a bug if it is problem in my setting please guide me to solve these problem
and thanks in advance

[Anonymous]

ooh this happened because render was by internal engina and not lightwork