Item lookup unable to search by letter after changing the default view

I am currently using GP2010 SP2 11.00.1752.

I change the default view on the item lookup. Now, whenever I enter a letter in the item number field and then click on the item lookup button.

The view does not return the result with the letter instead showing the 1st item number.

Example: I enter "W" in the item number field and then click on the item lookup.

The view result does not return the item number beginning with "W" instead it shows the first item "A"

Is there anyway that i can do so that i search by letter in the item lookup?

Thank you.