[HLSL] Normal mapping hates me

float4x4 world;        // World matrix
float4x4 viewproj;     // View*projection matrix
float4x4 worldviewit;  // The inverse transpose of the view*world matrix
float4 WorldLight;     // The light position in world

	// Multiply vertex by world & viewproj matrix
	output.pos=mul(float4(input.pos,1.0f),world);
	output.pos=mul(output.pos,viewproj);
	
	// Get the vertex normal and multiply it by the world matrix
	float4 normal=mul(float4(input.norm,1.0f),world);
	
	// Get the position of the vertex in world space
	float4 posWorld=mul(float4(input.pos,1.0f),world);
	
	// Get light vector
	float3 lightv=normalize(WorldLight-posWorld);
	
	// Calculate tan, binormal and normal by multiplying them with the inverse transpose of the view*world matrix 
	float3 tan=mul(float4(input.tan,1.0f),worldviewit).xyz;
	float3 bin=mul(float4(input.binorm,1.0f),worldviewit).xyz;
	float3 norm=mul(float4(input.norm,1.0f),worldviewit).xyz;
	
	// Tangent space matrix
	float3x3 tbnm=float3x3(tan,bin,norm);
	
	// Put light into tangent space
	output.light=mul(tbnm,lightv);
	
	// Texcoord
	output.texcoord=input.texcoord;

// Get the normal from the normal map
	float3 bump=2*normalmap.Sample(sampler1,input.texcoord).rgb-1.0f;
	
	// Light vector
	float3 light=normalize(input.light);
	
	// Light power 
	float diff=saturate(dot(bump,light));	
	
	// Color*light power	
	return float4(0.8f,0.0f,0.0f,1.0f)*diff;