Query gives not result

I have a quite simple table with different values. When I search a specific column no results are given. What could be the error?

For example I search for an "id":

db=# select * from table where id = 160000;
 x  | y  | alt  |   lat    |   lon    |   id   
----+----+------+----------+----------+--------
 80 | 80 | 2044 | 46.80125 | 12.99875 | 160000
(1 row)

Then I search for all "lat" with this value (limited to 1):

db=# select * from table where lat = 46.80125 limit 1;
 x | y  | alt  |   lat    |   lon    |  id   
---+----+------+----------+----------+-------
 1 | 80 | 1365 | 46.80125 | 12.00125 | 31921
(1 row)

But with the same search for "lon" I get no result where there should be:

db=# select * from table where lon = 12.99875;
 x | y | alt | lat | lon | id 
---+---+-----+-----+-----+----
(0 rows)

I did VACUUM and ANALYZE and now I don't know what to do else.