osmesa renders artifacts and demo app problem for mesa versions 10.6 - 11.1

Hi,
I'm quite new to mesa3d and openGL. I'm trying to make off-screen rendering
with osmesa. First I've build mesa 10.5.9 with MSVC 12 and it almost
worked. I'm drawing triangles using glBegig(GL_TRIANGLES) and for osmesa I
received artifacted renders (comapred to freeglut, osmesa renders have some
lines of 0 value - both render examples are attached in this message). I
was using exactly the same algorithm but changed freeglut to osmesa
library.

I've also tried to build new mesa versions 10.6.x and 11.0.1 (also with
MSVC 12.0) but I have problems with running osmesa demo project:
glGetIntegerv(GL_DEPTH_BITS, &z); glGetIntegerv(GL_STENCIL_BITS, &s);
glGetIntegerv(GL_ACCUM_RED_BITS, &a); gives -858993460 values, and
application doesn't render anything (empty buffer).

Do You know what can couse this two problems? Do You need any other
informations?
-- 
Best regards
Jacek Blumenfeld