[help][shader] if using compile ps_3_0 texture gets transparent

[Pirulax]

So, I have a shader:
 

float4 PixelShader3Function(float2 UVCoords : TEXCOORD0) : COLOR0
{
    return float4(0, 0, 0, 1);
}

technique Normal
{
    pass P0
    {     
        PixelShader = compile ps_3_0 PixelShader3Function();
    }
}

Which should make the texture black, but instead it makes it transparent.
But, if I use compile  ps_2_0 instead it works just fine, and turns my texture into black.
Anyone any idea?