How to new a linetype with dwg_add_LTYPE()?

[blkXu]

The code below is how I tried to add a line type. But it doesn't work（can't find the customized line type in the created dwg file）.
Can someone help me with it?

    Dwg_Object_LTYPE* lineType = dwg_add_LTYPE(dwgData, "Dash");
lineType->description = dwg_add_u8_input(dwgData, "Dash");
lineType->flag = 64;
lineType->pattern_len = 30;
lineType->num_dashes = 2;

lineType->dashes = new Dwg_LTYPE_dash;
lineType->dashes->parent = lineType;
lineType->dashes->length = 12;
lineType->dashes->complex_shapecode = 0;
lineType->dashes->style = new Dwg_Object_Ref;
lineType->dashes->style->obj = nullptr;
lineType->dashes->style->handleref.code = 5;
lineType->dashes->style->handleref.size = 0;
lineType->dashes->style->handleref.value = 0;
lineType->dashes->style->handleref.is_global = 0;
lineType->dashes->style->absolute_ref = 0;
lineType->dashes->style->r11_idx = 0;
lineType->dashes->x_offset = 0;
lineType->dashes->y_offset = 0;
lineType->dashes->scale = 1;
lineType->dashes->rotation = 0;
lineType->dashes->shape_flag = 0;
lineType->dashes->text = nullptr;