Upload caption update does not work

Hello,
I need to update the Upload field caption. Calling setCaption method does not work.
Is there another way to do this ?
Thanks.
 

The method for some reason is 
setButtonCaption 

I guess this is just for the toggle button itself. I need to change the upload field's label.
As in the sample :

Upload upload = new Upload("Upload it here", receiver);

I would like to change "Upload it here" label. This might be done using setCaption() method, isn't it ?

The problem is fixed. There were a bug,  setCaption was not called on the Upload component but on the parent abstract component.