What is the actual SPARQL Update you are reading in with this line:
UpdateRequest request = UpdateFactory.read("turtle.ttl");
Without knowing what the actual SPARQL Update is it is hard to say what is going wrong.
Guesswork...
Based on your commented out example are you trying to do something like the following:
LOAD <file:local.ttl> INTO GRAPH <http://graph>
If this is the case then this will not work, the remote server does not have access to your local file system so this command is not going to work.
Also file:local.ttl
is actually an invalid URI anyway, a file URI should look like file:///local.ttl
.
Edit
Per the comment I think your problem may be down to the Graph URIs being used, in all your examples you are using relative URIs so your data may not be going in the graph you expect. It's likely your data is being inserted but not into the graph you expect, if you don't have too much data you could try the following query to dump all data in named graphs to see if the data has gone somewhere:
SELECT * WHERE { GRAPH ?g { ?s ?p ?o } }
Or if you are expecting to have a small number of named graphs in the store the following will list out named graphs so you can see if you have any unexpected graphs:
SELECT DISTINCT ?g WHERE { GRAPH ?g { } }
Generally speaking it is always a good idea to use absolute URIs to ensure you are creating the data you expect in the graph you expect, relative URIs are error prone because they can resolve to different absolute URIs depending on the context in which they are resolved.