Call glDrawArrays on iPohone and then Error

Unity's GL class is too slow to many (tens of thousands~ ) lines.
So I'm trying to draw lines by native glDrawArrays call.

I called the obj-c function bellow in OnPostRender of Main Camera, but nothing was drawn,
and error message "OpenGLES error 0x0502" was printed.

 void drawLines(){
     static const GLfloat vertices[] = {
         -1.0f, -1.0f, 0,
         -1.0f, 1.0f,  0,
         1.0f,  1.0f, 0,
         1.0f, -1.0f, 0,
     };
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glVertexPointer(3, GL_FLOAT, 0, vertices);
     glEnableClientState(GL_VERTEX_ARRAY);
     glDrawArrays(GL_LINE_STRIP, 0, 4);
 
 }

What is wrong?