jQuery Grid Plugin - jqGrid

I'm using the jqgrid v4.6.0

In the seach screen, if you remove all rules defined and add a new rule; the search rules of this new rule do not apply.

It can be simulated in the demo application as well (Searching –> Validation in serach)

Steps to simulate:

• Load the above demo. load the seach screen (by clicking  'Find records' button).
• The screen will load with one rule. Remove this rule
• Click the add rule button and add a rule.
• Then click the 'Find' Button without entering any value.
• The screen gets closed, even when the search rule for 'Inv No' is indicated as required.

Expected Result: 

• When the find button is click, the validation should fire and saying the 'Inv No' is required.

Plesae let me know how i can correct this issue, or if there is a work around for it.

Thanks in Advance

InsI