DX11 draw a solid line

Hi everybody !

I just try to render lines in DX11.  

VS

cbuffer cbPerObject
{
matrix WVP;
matrix Ortho;
};

struct VS_OUTPUT
{
float4 Pos : SV_POSITION;
float4 Color : COLOR;
};

VS_OUTPUT VS(float4 inPos : POSITION, float4 inColor : COLOR)
{
VS_OUTPUT output;
output.Pos = mul(inPos,    Ortho);
output.Color = inColor;

return output;
}

PS
cbuffer cbPerObject
{
matrix WVP;
matrix Ortho;
};

struct VS_OUTPUT
{
float4 Pos : SV_POSITION;
float4 Color : COLOR;
};

float4 PS ( VS_OUTPUT input ) : SV_TARGET
{
return input.Color;
}

Lines has gaps

1) Why does it happened  ?

2) How to draw solid lines in DX11 ?