Is there a problem whith the ufactor for kway partitionning?

Hi everybody,
I'm trying to use the new version of hmetis (hmetis-2.0pre1) to partition an hypergraph.
But it seems like the ufactor have no influence. I think i don't use it properly!!
I did a test in a simple image (white square on dark background) and i created the corresponding hypergraph (40000 nodes and 40000 edges).

When i used ufactor=20.0, i got this:
Partition Sizes & External Degrees:
( 10073.000)[ 250.000] ( 9781.000)[ 98.000] ( 10073.000)[ 266.000]
( 10073.000)[ 418.000]
The partition sizes are almost the same, whereas, according to the definition of ufactor, the size of the largest partition can be 1.20 * (40000/4) = 12000.

When i used ufactor=150.0, i got this:
Partition Sizes & External Degrees:
( 9717.000)[ 98.000] ( 10027.000)[ 249.000] ( 10129.000)[ 262.000]
( 10127.000)[ 413.000]
wheareas the size of the largest partition can be 2.50 * (40000/4) = 25000.
I dont understand why, because the results i get are not relevant.

Here is the command line i did:
./hmetis2.0pre1 -ptype kway -ctype gfc1 -ufactor 150.0 -nruns 25 -nvcycles 5 -cmaxnet 50 /data/lienou/clc/progs2/hypergraphes/testhgraph.graph 4
Can anybody help me please?