Static batching not working

Hi everybody! Please help me solve my problem.

I have scene with similar objects (fences) they have similar meshes, materials and static param. At startup unity crates one big mesh. It must draw all bences by one draw call but actually it draws each by separate calls - one or couple fences. As result - low fps. Why that?

Here is screenshot where you can see frame debugger and draw queue.How can I draw them by one draw call? Thanks.