glsl - Ward model implementation: specular component too weak

I'm trying to implement the Ward shading model, the anisotropic, computationally efficient version:

This is how I made it:

float alphaX=0.5, alphaY=0.5; // asinotropic roughness
float minFloat= 1.e-6; 

vec4 Ward(vec3 L, vec3 N, vec3 V)
{

    vec3 H= normalize(L+V);
    float NdotL= max(dot(N,L),0.0);
    float NdotV= max(dot(N,V),0.0);

    vec3 e= vec3(1.0,0.0,0.0);
    vec3 T= normalize(cross(N,e));
    vec3 B= normalize(cross(N,T));
    float HdotT= max(dot(H,T),0.0);
    float HdotB= max(dot(H,B),0.0);
    float HdotN= max(dot(H,N),0.0);


    float beta= -2.0 * ( pow(HdotN/alphaX, 2.0) + pow(HdotB/alphaY,2.0) ) / (1.0 + HdotN);
    float den= max(minFloat, 4.0 * pi * alphaX * alphaY * sqrt(NdotL * NdotV) );
    vec4 specular= Ps * 1.0/den * exp(beta);
    return (Pd + specular) * NdotL;
}

But I get a result similar to a lambertian surface or Oren-Nayar model, where the specular component is absent:

Answer

The problem was solved by just changing the e vector to (0,0,-1). I also needed to clamp the returned color:

return clamp((Pd + specular) * NdotL, 0.0, 1.0);

Result: