Combobox not working

Hi all,
I have written a code for testing GUI for an windows based application.The below code has to select a string from drop down list which is not working please help me to resolve this.i couldnt trace class and inatance so i use control id to handle it
ControlCommand($a,"", 1150, "ShowDropDown", "")

ControlCommand($a, "", 1150, "SetCurrentSelection",$strCombo2)

If @error == 1 Then
FileWriteLine($file, 'Error: ComboBox2 Fail')
Else
FileWriteLine($file, 'ComboBox2: Select Image Success')
EndIf
Sleep(1000)