Vertex attribute is not being interpolated at all - c++

Question

I assign each vertex a unique set of coordinates and i am expecting the fragment in fragment shader to have interpolated value for that varying variable. Problem is, in fragment shader value always remains 0.0. How can i fix that. I am using opengles 2.0 with glsl version 1.2.
Vertex shader:
attribute vec4 Position;
attribute vec4 SourceColor;
attribute vec3 BaryCentricCoord;
varying vec4 DestinationColor;
uniform mat4 Projection;
uniform mat4 Modelview;
attribute vec2 TexCoordIn;
varying vec2 TexCoordOut;
varying vec3 vBC;
void main() {
vBC = BaryCentricCoord;
DestinationColor = SourceColor;
gl_Position = Projection * Modelview * Position;
TexCoordOut = TexCoordIn;
};
Fragment shader:
varying vec4 DestinationColor;
varying vec2 TexCoordOut;
varying vec3 vBC;
uniform sampler2D Texture;
uniform int TexEnabled;
float edgeFactor();
void main() {
if (TexEnabled == 1) {
gl_FragColor = texture2D(Texture, TexCoordOut) * DestinationColor;
} else{
gl_FragColor = vec4(DestinationColor.xyz, edgeFactor());
}
}
float edgeFactor() {
vec3 d = fwidth(vBC);
vec3 a3 = smoothstep(vec3(0.0), d*1.5, vBC);
return min(min(a3.x, a3.y), a3.z);
};
Vertex data:
float vertices[] {
p1.x - deltaX, p1.y + deltaY, 0.0f, //top-left
p2.x - deltaX, p2.y + deltaY, 0.0f, //top-right
p2.x + deltaX, p2.y - deltaY, 0.0f, //bottom-right
p2.x + deltaX, p2.y - deltaY, 0.0f, //bottom-right
p1.x + deltaX, p1.y - deltaY, 0.0f, //bottom-left
p1.x - deltaX, p1.y + deltaY, 0.0f //top-left
};
Barycentric coordinates i am passing (each set of 3 corresponds to a vertex):
// R
data[0] = 1.0;
data[1] = 0.0;
data[2] = 0.0;
// G
data[3] = 0.0;
data[4] = 1.0;
data[5] = 0.0;
// B
data[6] = 0.0;
data[7] = 0.0;
data[8] = 1.0;
// B
data[9] = 0.0;
data[10] = 0.0;
data[11] = 1.0;
// G
data[12] = 0.0;
data[13] = 1.0;
data[14] = 0.0;
// R
data[15] = 1.0;
data[16] = 0.0;
data[17] = 0.0;
Enabled :
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable( GL_BLEND );
Passing data as: glDrawArrays(GL_TRIANGLES, 0, 6);