Ajax Toolkit Calendar Extender Error

I have an asp.net website deployed to a staging server and a production server. On my staging server the calendar extender works fine. However, it comes up a blank calendar and I get a java script error on my production server. Both have the same exact code deployed (minus connection strings in web config), the same versions of .NET, and the same versions of the AjaxControlToolkit dll.

Production Server:

Error:

ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1 Uncaught TypeError: Cannot read property 'getFullYear' of null at Sys.Extended.UI.CalendarBehavior._parseTextValue (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at Sys.Extended.UI.CalendarBehavior.get_selectedDate (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at Sys.Extended.UI.CalendarBehavior._getEffectiveVisibleDate (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at Sys.Extended.UI.CalendarBehavior._switchView (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at Sys.Extended.UI.CalendarBehavior.show (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at Sys.Extended.UI.CalendarBehavior._element_onfocus (ScriptResource.axd?d=NISXSzp87hD3qcCkP6NEPuF9CcnK5I-ufPjsh34laJN_X0aVHxlrSCRTcuVNdBlHJPhDZIUvEREh5VBuThlsgo_BghBpg0ddHeQysAHm-fvIzsJbjZge0NiahMLqHuR00&t=ffffffff949e5296:1) at HTMLInputElement. (MicrosoftAjax.js:6) at HTMLInputElement.b (MicrosoftAjax.js:6)

Staging:

Any ideas what may cause this? My guess would be some type of version mismatch somewhere, but I can't seem to find one. Let me know if additional information is required.