Date picker error when the text box's id=1

I use the text box id to store an information(id of database). When the id="1", the following error(dump from opera) occurs:

JavaScript - http://football/index.php?q=football/match

Event thread: click

Error:

name: TypeError

message: Statement on line 1172: Cannot convert undefined or null to Object

Backtrace:

Line 1172 of linked script http://football/sites/all/modules/football/js/ui.datepicker.js?w

return inst.settings[name] !== undefined ?

Line 765 of linked script http://football/sites/all/modules/football/js/ui.datepicker.js?w

var rangeSelect = this._get(inst, 'rangeSelect');

Line 1 of function script

jQuery.datepicker._selectDay('#1',9,2008, this);

...

stacktrace: n/a; see 'opera:config#UserPrefs|Exceptions Have Stacktrace'

The same error is also apply to firefox 3 and internet explorer 6.

The others id are working fine.