Fixed small bug that occurred when reading an un-open file

DaqFileIO.cxx

@@ -2,7 +2,7 @@
 ///
 // DAQ low level IO Library
 // 
-// $Id: DaqFileIO.cxx,v 1.19 2011/10/07 20:48:06 iowa\vhorosewski Exp $
+// $Id: DaqFileIO.cxx,v 1.20 2011/12/28 16:12:05 iowa\vhorosewski Exp $
 // Date: March, 2005
 // Author: Yiannis Papelis
 //
@@ -1838,6 +1838,8 @@ CDaqLowLevelIo::ReadDataForOneFrame(
 
 	for (idx=0; idx<numEntriesInThisRecord; idx++) {
 		int chId;
+		if (m_pFile == NULL) return eDAQ_READ_ERROR;
+
 		if ( fread(&chId, sizeof(int), 1, m_pFile) != 1 ) return eDAQ_READ_ERROR;
 
 		if ( chId >= m_NumEntries || chId < 0 ) {