How can i get data from another document when i creat a new document on my XPage?

How can i get data from another document when i creat a new document on my
XPage?

I've start to develop XPage 7 weeks ago, and i have a problem with
"getting data".
On my first page i have a view with a lot of documents, and a button who
redirect me on a new page, to create a new document. On my first page i
can select a document and when i click on the button i put my id document
selected on a sessionSCope.
Button script:
var viewPanel=getComponent("viewPanel1");
var docIDArray=viewPanel.getSelectedIds();
var docUID=database.getDocumentByID(docIDArray[0]).getUniversalID();
sessionScope.put("docUID", docUID);
context.redirectToPage("AjoutSuivi");
On my new XPage i want to get some data on my selected document so on
clientLoad of the XPage i execute this script:
var docUID = sessionScope.get("docUID");
var doc:NotesDocument = database.getDocumentByUNID(docUID);
getComponent("contactname1").setValue(doc.getItemValueString("ContactName"));
On my database i have a field "ContactName" and on my XPage i have a field
contactname1. I have try with "database.getDocumentByID(docUID)" and i'm
sure that "database" is the good link of the database.
When i try it, there is nothing on the field contactname1 have u an idea
why that's doesn't work ?
So much thank's if you can help me
Yann
PS: sorry for my bad english