Problem to update entity with java api - checkout and getting the correct entity

hello,

I'm building api project with java and i have few problems to update entities:

I'm using sdk 1.7, win 7, 64 bit,

first problem - checkout

the scenario:

1. qcAuthenticate - works

2. qcLock - works

3. qcCheckout  :

the java code :

public static String entity= "tests/7747";

URL url = new URL("http://"+ALMServer+"/qcbin/rest/domains/"+DOMAIN_NAME+"/projects/"+PROJECT_NAME+"/"+entity+"/versions/check-out");

conn = (HttpURLConnection) url.openConnection();
cm.setCookies(conn);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/xml");
conn.setRequestProperty("Accept", "application/xml");

conn.setRequestProperty("Input", "<VersionParameters><Comment>blablabla</Comment></VersionParameters>");

System.out.println(conn.getResponseMessage());
System.out.println(conn.getResponseCode());

System.out.println(conn.getHeaderFields());

the server answer :

Bad Request
400
{null=[HTTP/1.1 400 Bad Request], Date=[Wed, 03 Jul 2013 08:46:29 GMT], Transfer-Encoding=[chunked], Connection=[close], Content-Type=[application/xml], X-Powered-By=[Servlet 2.5; JBoss-5.0/JBossWeb-2.1], Server=[Apache-Coyote/1.1]}

I tried many ways and still i got : 400 , what should i do diffrent? do you have any example in java for this?

second problem - get to an entity

I'm mannage to get only simple entities for example : defect/1 or tests/6632

how do i get to more complexed entity like :

test lab -> root -> folder/name1 -> subFolder/name2 -> subSubFolder/name3 -> Test-set/id(2651) ->test ?

can you please send me a java example ?

Thanks,

and a very good day!

Or