NSDateFormatter producing (null) SQLite and iOS 5.1 - objective-c

Question

Maybe somebody can help explain why I am getting a null value when converting a string to a date. It all looks right but I'm obviously missing something here.
Some background:
This iPad app will be used in different countries and I will need to do a calculation on the date to see if 90 days have passed since a user last logged in.
I have a SQLite Database with a DateLastIn field set as TEXT
My Object has a DateLastIn property set as NSDate
When populating my record object I set up a NSDateFormatter as such..
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"]; // SQLite default date format
Then I read in the DateLastIn (Using FMDB wrapper for SQLite).
// test SQLite as String
NSString *testDate = [results stringForColumn:#"DateLastIn"];
NSLog(#"DateLastIn straight from DB (string) shows %#", testDate);
Result:
DateLastIn straight from DB (string) shows 2012-04-23 18:20:51
All is good so far. Next I test converting this to an NSDate object e.g
NSDate *aDate = [[NSDate alloc] init];
aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
Result:
Using formmater on string date results in: (null)
I have tried DATETIME in SQLite, I've tried using NSString in my object instead of NSDate and seem to be going around in circles.
Any help much appreciated.

Answer 1

NSDateFormatter uses the format patterns from the Unicode Technical Standard #35.
For the hour format, you need HH (Hour [0-23]) not hh (Hour [1-12]).

Answer 2

I changed your date format to HH not hh and it works. Here is my test code....
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"]; // SQLite default date format
// test SQLite as String
NSString *testDate = #"2012-04-23 18:20:51";
NSDate *aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);