The SCAN_SetReaderP arams 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.Actio ns.Enable();
....
_myReader.readN otify += (Some EventHanlder)
....
_myreader.Actio ns.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>
OperationFailur eException
SCAN_SetReaderP arams
At
Symbol.Barcode. ReaderParams.Se tReaderParams()
At Symbol.Barcode. Actions.Read()
At <AppName>.sunWM SCycleCountDire ctives.selScanL ocation()
At System.Windows. Forms.Control.O nGotFocus()
At System.Windows. Forms.Control.W nProc()
At System.Windows. Forms.Control_I nternalWnProc()
At Microsoft.AGL.F orms.WL.SetFocu s()
At System.Windows. Forms.Control.F ocus()
At <AppName>.sunWS CycleCountDirec tives.selAsile_ Modified()
At System.Windows. Forms.ListContr ol.OnSelectedVa lueChanged()
At System.Windows. forms.ListContr ol.OnSelectedIn dexChanged()
At System.Windows. Forms.ComboBox. onSelectedIndex Changed() "

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:01.43.4 41; and other one's OS
version: 05.00.000 , OEM Version:01.20.0 000, IPL Version:01.42.4 40;

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

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

Thanks,
Andy