Invalid column name ??

     I did a table export from Acess 2002 to Oracle9i.
     When I  "Select * from table1" I see all of the variables.
     When I  select individual variables ("select var1 from table1")
     I sometimes get a value.  For other variables I get
      ORA 00904  Invalid column name.

     I am using the exact spelling the the variable name I see in my
     Select *  statement.

       Any ideas?

               thanks,   tom g