PHP Header redirect not working

1) There should be NO output (i.e. echo... or HTML parts) before the header(...); command.

2) After header(...); you must use exit();

3) Remove any white-space(or newline) before and after ?> tags.

4) Check that php file (and also other .php files, that are included) -
they should have UTF8 without BOM encoding (and not just UTF-8). Because default UTF8 adds invisible character in the start of file (called "BOM"), so you should avoid that !!!!!!!!!!!

5) Use 301 or 302 reference:

header("location: http://example.com",  true,  301 );  exit;

6) Turn on error reporting. And tell the error.

7) If none of above helps, use JAVASCRIPT redirection (however, discouraged method), may be the last chance in custom cases...:

echo ""; exit;