The SCAN_SetReaderParams Error occured when using SMDK (SymbolMobility Development Kit)1.5 for .NET

[Fuc]

hi experts,

We are using the Symbol MC9090G scanners, and use the symbol SMDK 1.5
for .NET to develop the WinCE form application, the tools we are using
is VS2005 professional and C#.

We are using Symbol.Barcode namespace class to read barcode and do
some logic etc. the code just like:

Symbol.Barcode.Reader _MyReader = new Reader();
....
_myReader.Actions.Enable();
....
_myReader.readNotify += (Some EventHanlder)
....
_myreader.Actions.Read();

the code above is very similar with the SMDK 1.5 sample
CS_ScanSample1. all is ok on one scanner, but, on the other scanner
it always prompt the error:
"Error
<AppName>
OperationFailureException
SCAN_SetReaderParams
At
Symbol.Barcode.ReaderParams.SetReaderParams()
At Symbol.Barcode.Actions.Read()
At <AppName>.sunWMSCycleCountDirectives.selScanLocati on()
At System.Windows.Forms.Control.OnGotFocus()
At System.Windows.Forms.Control.WnProc()
At System.Windows.Forms.Control_InternalWnProc()
At Microsoft.AGL.Forms.WL.SetFocus()
At System.Windows.Forms.Control.Focus()
At <AppName>.sunWSCycleCountDirectives.selAsile_Modif ied()
At System.Windows.Forms.ListControl.OnSelectedValueCh anged()
At System.Windows.forms.ListControl.OnSelectedIndexCh anged()
At System.Windows.Forms.ComboBox.onSelectedIndexChang ed() "

I don't know why this come up. there is some differences between two
scanners.
the good one 's OS Version: 05.01.0476, OEM name: SYMBOL MC9090G, OEM
Version: 01.35.0002, IPL version:01.43.441; and other one's OS
version: 05.00.000 , OEM Version:01.20.0000, IPL Version:01.42.440;

I'm not sure if this system little difference make it.

Any help is highly appreciated!! and sorry for some rusty english.

Thanks,
Andy