SendKey {TAB} is not working on IE9

Question

I am trying to execute below scenario on IE9 with Windows 7 using UFT 11.53

User selects a value from DojoFilterCombobox, after selecting a value,table grid populates data based on value selected.

For this I am selecting a value from combobox and tabbing out to other field so that the grid is populated.

I am calling below function after setting a value in combobox:

 Function syncEditField()
    Set W = CreateObject("WScript.Shell")
    wait(3)
    W.SendKeys "{TAB}"
    wait(3)
End Function

This is not tabbing out to other field. This code is working fine on IE8 with Windows 7

Could any one please help me on this?