diff -Naur lammps-19Jan08/src/fix_ave_time.cpp lammps-20Jan08/src/fix_ave_time.cpp
--- lammps-19Jan08/src/fix_ave_time.cpp	2008-01-09 14:56:57.000000000 -0700
+++ lammps-20Jan08/src/fix_ave_time.cpp	2008-01-17 13:58:19.000000000 -0700
@@ -144,7 +144,7 @@
       int ifix = modify->find_fix(ids[i]);
       if (ifix < 0)
 	error->all("Fix ID for fix ave/time does not exist");
-      if (argindex[i] && modify->fix[ifix]->scalar_flag == 0)
+      if (argindex[i] == 0 && modify->fix[ifix]->scalar_flag == 0)
 	error->all("Fix ave/time fix does not calculate a scalar");
       if (argindex[i] && modify->fix[ifix]->vector_flag == 0)
 	error->all("Fix ave/time fix does not calculate a vector");