Shadow not rendered correctly - glsl

Question

I am trying create shadow using shadow maps. I believe that shadow map is rendered well.
It seems that sphere's shadow is not in the correct place, so how would I go about fixing that? Also why is there a black ring around the sphere and how to eliminate it?
In the shadow map vertex shader
gl_Position = u_depthMatrix * worldCoord;
In the shadow map fragment shader
fragmentdepth = gl_FragCoord.z;
vs.glsl
uniform mat4 u_Model;
uniform mat4 u_View;
uniform mat4 u_Persp;
uniform mat4 u_InvTrans;
uniform vec3 u_LightColor;
uniform vec3 u_LightDirection;
uniform vec3 u_EyePos;
uniform mat4 u_depthBiasMatrix;
in vec3 Position;
in vec3 Normal;
in vec2 Texcoord;
out vec3 v_Normal;
out vec2 v_Texcoord;
out vec3 v_Position;
out vec3 v_PositionMC;
out vec4 shadowCoord;
void main(void)
{
v_Normal = (u_InvTrans*vec4(Normal,0.0)).xyz;
vec4 world = u_Model * vec4(Position, 1.0);
vec4 cameraCoord = u_View * world;
v_Position = cameraCoord.xyz;
shadowCoord = u_depthBiasMatrix * world;
gl_Position = u_Persp * cameraCoord;
}
fs.glsl
uniform sampler2D shadowMap;
uniform vec3 u_LightColor;
uniform vec3 u_LightDirection;
uniform vec3 u_EyePos;
uniform vec3 u_Ka;
uniform vec3 u_Kd;
uniform vec3 u_Ks;
in vec3 v_Normal;
in vec2 v_Texcoord;
in vec3 v_Position; //coordinate of vertex in camera coordinate system
in vec4 shadowCoord;
void main(void)
{
vec3 v_Normal1 = normalize(v_Normal);
//Diffuse Lighting
vec3 diff = normalize(u_LightDirection - v_Position);
float diffuse = max(dot(diff , v_Normal1) , 0);
vec3 diffuseColor = diffuse * u_Kd * u_LightColor;
//Specular Lighting
vec3 v = normalize(vec3(u_EyePos - v_Position));
vec3 h = normalize(diff + v);
float sl = pow(max(dot(h, v_Normal1) , 0.0), 50);
if ( diffuse <= 0 ) sl = 0;
vec3 specularColor = sl * u_Ks * u_LightColor;
vec3 v_Color;
v_Color = u_Ka + diffuseColor + specularColor ;
//Shadow Part
vec3 shadowCoord3;
float shadowFactor = 1.0;
if(shadowCoord.w > 0 )
{
shadowCoord3 = shadowCoord.xyz / shadowCoord.w ;
if ( texture2D( shadowMap, shadowCoord3.xy ).z < shadowCoord3.z)
{
shadowFactor = 0.2;
}
}
gl_FragColor = shadowFactor * vec4(v_Color , 1);
}