Question about zero render issue

[Yi tiger]

Hi there,

recently I'm working on a PDF reader application which use FreeType to render 
text. we had a pdf file which number zero render as below
[cid:1d617ea9-2063-4ad8-9849-51c3d0598896]
I extract the font from PDF and attached, when I use FontForge open the font I 
saw.
[cid:c589c33c-2ea3-4dae-9bfe-3cc603b94370]

and then I use FreeType read its bitmap and print to console, I saw
[cid:71169b3a-d780-4b82-b343-e6dbec237d71]
error = FT_Load_Glyph(pFTFace, 3, FT_LOAD_DEFAULT);
error = FT_Get_Glyph(pFTFace->glyph, &glyph);
FT_Glyph_To_Bitmap(&glyph, FT_RENDER_MODE_NORMAL, 0, 1);

so I think the font itself has some issue, but I don't know what's wrong with 
the font (i have very little knowledge with the font)? can someone help?

PS.  very interesting Adobe Acrobat render zero correctly

Thanks in advance.

Tiger

font.cff
Description: font.cff