Description of problem:
When logical network is created via webadmin, it is not possible to change its properties later on via Edit Logical Networks dialog. OK button does not work, so it is not possible to save changes. However if override MTU box is checked and unchecked, OK button works.

Version-Release number of selected component (if applicable):
ovirt-engine-webadmin-portal-3.0.0_0001-3.git4364f1b.fc16.x86_64

How reproducible:
always

Steps to Reproduce:
1.In webadmin go to Data Centers -> your data center -> logical network -> nee
   a) fill in Name field
   b) leave the rest as is, press OK
   
2.Select the new network -> edit
   a) change Name field
   b) press OK
   result: nothing happens

3.Tick Override MTU -> untick Override MTU -> press OK
   result: changes get commited
  
Actual results:
Wihout tick/untick Override MTU, ok button does not work

Expected results:
Ok button function should not depend on Override MTU checkbox

Additional info:
when OK button does not work, no logs are produced