-extern void MSC_SendData(tUSBInterface *Dev, size_t CmdLen, const void *CmdData, size_t DataLen, const void *Data);
-extern void MSC_RecvData(tUSBInterface *Dev, size_t CmdLen, const void *CmdData, size_t DataLen, void *Data);
+extern int MSC_SendData(tUSBInterface *Dev, size_t CmdLen, const void *CmdData, size_t DataLen, const void *Data);
+extern int MSC_RecvData(tUSBInterface *Dev, size_t CmdLen, const void *CmdData, size_t DataLen, void *Data);