How to get Comment value of Activity

Hello Guys,

I am try get Comment value on post,pre and Server . but I am getting null value . code is below .

Can you suggest me ? How can i do it?

/*ND Add Comment On AVL ECR From Activity Assignment*/
Innovator inn=this.getInnovator();
string activityId = this.getID();
Aras.Server.Security.Identity roleIden = Aras.Server.Security.Identity.GetByName("Innovator Admin");
bool SetPermission = Aras.Server.Security.Permissions.GrantIdentity(roleIden);
try
{

Item WorkflowProcessActivity=inn.newItem();
WorkflowProcessActivity.loadAML("<Item type='Workflow Process Activity' action='get' select='id,related_id,source_id'>"+
"<related_id condition='eq'>"+activityId+"</related_id>"+
"</Item>"
);
Item WorkflowProcessActivityR=WorkflowProcessActivity.apply();
int WorkflowProcessActivityCount=WorkflowProcessActivityR.getItemCount();
if(WorkflowProcessActivityCount==1)
{
String state="Active" ;
String WorkflowProcessID=WorkflowProcessActivityR.getProperty("source_id");
Item WorkflowProcess=inn.newItem();
WorkflowProcess.loadAML("<Item type='Workflow Process' action='get' select='id,name,state'>"+
"<id condition='eq'>"+WorkflowProcessID+"</id>"+
"<state condition='eq'>"+state+"</state>"+
"</Item>"
);

Item WorkflowProcessR=WorkflowProcess.apply();
int WorkflowProcessCount=WorkflowProcessR.getItemCount();
if(WorkflowProcessCount==1)
{
String AVLNO=WorkflowProcessR.getProperty("name");
Item AVLECR=inn.newItem();
AVLECR.loadAML("<Item type='ND Part AVL ECRs' action='get' select='id,nd_design_reviewer,nd_avl_ecr_no'>"+
"<nd_avl_ecr_no condition='eq'>"+AVLNO+"</nd_avl_ecr_no>"+
"</Item>"
);
Item AVLECRR=AVLECR.apply();
int AVLECRRCount=AVLECRR.getItemCount();
if(AVLECRRCount==1)
{

Item ActivityAssignment=inn.newItem();
ActivityAssignment.loadAML("<Item type='Activity Assignment' action='get' select='id,related_id,source_id,comments'>"+
"<source_id condition='eq'>"+activityId+"</source_id>"+
"</Item>"
);
Item ActivityAssignmentR=ActivityAssignment.apply();
int ActivityAssignmentCount=ActivityAssignmentR.getItemCount();
//return inn.newError("ActivityAssignmentCount "+ActivityAssignmentCount);
if(ActivityAssignmentCount==1)
{
string Activitycomments=ActivityAssignmentR.getProperty("comments");
return inn.newError("Activitycomments "+Activitycomments);
Item AVLECRs=inn.newItem("ND Part AVL ECRs","edit");
AVLECRs.setAttribute("slect","id,nd_design_reviewer,nd_avl_ecr_no,nd_reviewer_comments");
AVLECRs.setID(AVLECRR.getID());
AVLECRs.setProperty("nd_reviewer_comments",Activitycomments);
AVLECRs.apply();
//AVLECRR



}

}

}
}
}
finally{
if (SetPermission ==true) {
Aras.Server.Security.Permissions.RevokeIdentity(roleIden);
}
}
return this;

Regards

Ashok Kumar Yadav