st: 'if' with labels but finds no observations

["Paul O'Brien" <paul.obrien@afe2.org.uk>]

Dear All,

I am not sure what the problem is here, but 'if' is not working for   
some date labels.
year_f is OK up to 2000/1 but beyond that give no observations.


.egen year_f = ncyear(date_v), m(4)


. table year_f
----------------------
��year_f |�����Freq.
----------+-----------
�1997/98 |����44,023
�1998/99 |����42,654
��1999/0 |����42,944
��2000/1 |����42,127
��2001/2 |����41,520
��2002/3 |����41,463
��2003/4 |����40,057
----------------------


. table ageint if year_f==2000/1

----------------------
��ageint |�����Freq.
----------+-----------
������12 |���������5
������13 |��������36
������14 |�������131
������15 |�������346
etc


. table ageint if year_f==2001/2

no observations

r(2000);

But there are observations for year_f==2001/2

�. table ageint year_f

------------------------------------------------------------------------ 
-
          |                            year_f
   ageint | 1997/98  1998/99   1999/0   2000/1   2001/2   2002/3    
2003/4
---------- 
+--------------------------------------------------------------
       10 |       1        1                          2        1         
1
       11 |       2        2        2                 1        2         
1
       12 |       2        3        2        5        4        3         
7
       13 |      13       20       17       36       22       20        
12
       14 |      73       49       64      131      110      101        
99
       15 |     238      259      238      346      362      302       
325

If I try -list- I get the same thing:

. list if year_f==2000/1

�Observation 129622

���clin_s~e����������RC���clin_w~k������������������connum�����������2�� 
�����date���15-Feb-01��������dob���04-Apr-63

etc

�
Observation 129623

���clin_s~e����������RC���clin_w~k�������D- 
CON�����connum�����������1�������date���07-Feb-01��������dob���06-Apr 
-77

etc

�

. list if year_f==2001/2

This last command gives nothing.

Help gratefully received.

Paul

Dr Paul O'Brien
Westside Contraceptive Services
Raymede Clinic, Exmoor St, London
W10 6DZ
020 8962 4450 - tel
020 8962 4451 - fax
07900 495 118 - mob

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/