hi can anyone help me regarding the smart card API SCardLocateCardsW here is the code i am sending which i have written [DllImport("winscard.dll", SetLastError = true)] internal static extern int SCardLocateCardsW(UInt32 hContext, [MarshalAs(UnmanagedType.LPTStr)] string mszCards, [In, Out] SCard_ReaderState[] rgReaderStates, int cReaders); int nbReaders; SCard_ReaderState[] readerState = new SCard_ReaderState[1]; // UInt32 eventState = readerState[0].m_dwEventState; readerState[0].m_dwCurrentState = (UInt32)CARD_STATE.UNAWARE; readerState[0].m_szReader = (string)reader; nbReaders = readerState.Length; string card1 = "Axalto Cryptoflex .NET"; //string[] card = { "Infineon SICRYPT CardModule Card", "Axalto Cryptoflex .NET" }; //card[0]= "Infineon SICRYPT CardModule Card"; //card[1]="Axalto Cryptoflex .NET"; //string card = ""; int nErrCode = SCardLocateCardsW(m_hContext,card1,readerState, nbReaders); if (nErrCode != 0) { string msg = "Failed SCardLocateCardsA error: " + nErrCode; throw new Exception(msg); } the code is throwing an error i am not knowing wht to pass in the mszcards can anyone help me i need this thanks in advance leela