MGFX weirdness when adjusting texCoord

Thanks, Tom!

Here’s the working shader now, works totally fine:

//refract.fx

#define DECLARE_TEXTURE(Name, index) \
    Texture2D<float4> Name : register(t##index); \
    sampler Name##Sampler : register(s##index)

#define SAMPLE_TEXTURE(Name, texCoord)  Name.Sample(Name##Sampler, texCoord)

DECLARE_TEXTURE(TextureSampler, 0);
DECLARE_TEXTURE(RefractSampler, 1);

float amt = 0.0f;

struct PS_INPUT
{
	float2 TexCoord : TEXCOORD0;
};

float4 Refract(float4 position : SV_Position, float4 color : COLOR0, float2 texCoord : TEXCOORD0) : COLOR0
{	
	float2 tex = texCoord;
	float offset = SAMPLE_TEXTURE(RefractSampler, texCoord).g;
	tex.x += offset * 0.01f;
	tex.y += offset * 0.01f;

	return SAMPLE_TEXTURE(TextureSampler, tex);
}

technique RefractTechnique
{
    pass P0
    {
        PixelShader = compile ps_4_0_level_9_3 Refract();
    }
}