Can't draw polygons with two side lighting

I am using glDrawArrays function and sets befor glLightModel(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE). Polygons are drawn with one side lighting. If I change glDrawArrays drawing to usage of glBegin( GL_TRIANGLES ) glEnd() glVertex() then the polygons are drawn with two side lighting. Someone could help me with the problem?

I found hint to solve the problem - to add aditionals lights with opossite directions.
But anyway would like to have correct solution of this problem.