black shadows in ue4

whenever i place any mesh or imported model, there are black shadows at the roof ,even after building the light and the roof texture is not visible, please see the attached image ,PLEASE help ,i m developing an open world game

please post a picture from UV layout (meshEditor->UV-Layer0 and Layer1 plz)

Try modifie the skylight. Make it brighter, make it movable or static. For me it always worked.