Problem in updating entity sevice record

i am doing a POC for update through Web Dynpro

I have made an entity sergvice with a field as fname-short text- i create a record in it as below and save its guid in a context varialbe

AFirstOne one = FirstOneServiceProxy.create();
one.setFname("hello");
one.getAspect().sendChanges();
wdContext.currentContextElement().setKey(one.getGuid());

Now i am trying to update the same record --

 
AFirstOne first = FirstOneServiceProxy.read
(wdContext.currentContextElement().getKey());
 if (first ==null)
{  wdComponentAPI.getMessageManager().reportSuccess("null");
	   }
else
{  wdComponentAPI.getMessageManager().reportSuccess("not null"); 
wdComponentAPI.getMessageManager().reportSuccess(first.getGuid());
first.setFname("bye");
first.getAspect().sendChanges();
}

The not null and guid is printed but the record is not updated inn the table

Can anyone plaes suggest me the reason for this?

What am i doing wrong ?