Index: trunk/Mars/mcore/fits.h
===================================================================
--- trunk/Mars/mcore/fits.h	(revision 16890)
+++ trunk/Mars/mcore/fits.h	(revision 16896)
@@ -1008,5 +1008,5 @@
 
     bool IsHeaderOk() const { return fTable.datasum<0?false:(fChkHeader+Checksum(fTable.datasum)).valid(); }
-    bool IsFileOk() const { return (fChkHeader+fChkData).valid(); }
+    virtual bool IsFileOk() const { return (fChkHeader+fChkData).valid(); }
 
     bool IsCompressedFITS() const { return fTable.is_compressed;}