I have a app that has been working fine for over a month, and now all of a sudden I get this. If you know please let me know.
TypeError: Error #1009: Cannot access a property or method of a null object reference. at mx.controls::AdvancedDataGridBaseEx/http://www.adobe.com/2006/flex/mx/ internal::getHeaderInfo()[C:\work\flex\dmv_automation\projects\datavis ualisation\src\mx\controls\AdvancedDataGridBaseEx.as:2366] at mx.controls::AdvancedDataGrid/http://www.adobe.com/2006/flex/mx/intern al::getHeaderInfo()[C:\work\flex\dmv_automation\projects\datavisualisa tion\src\mx\controls\AdvancedDataGrid.as:2147] at mx.controls::AdvancedDataGrid/getFieldSortInfo()[C:\work\flex\dmv_auto mation\projects\datavisualisation\src\mx\controls\AdvancedDataGrid.as: 6840] at mx.controls.advancedDataGridClasses::AdvancedDataGridHeaderRenderer/ge tFieldSortInfo()[C:\work\flex\dmv_automation\projects\datavisualisatio n\src\mx\controls\advancedDataGridClasses\AdvancedDataGridHeaderRender er.as:757] at mx.controls.advancedDataGridClasses::AdvancedDataGridHeaderRenderer/me asure()[C:\work\flex\dmv_automation\projects\datavisualisation\src\mx\ controls\advancedDataGridClasses\AdvancedDataGridHeaderRenderer.as:481 ] at mx.core::UIComponent/measureSizes()[C:\autobuild\3.2.0\frameworks\proj ects\framework\src\mx\core\UIComponent.as:5956] at mx.core::UIComponent/validateSize()[C:\autobuild\3.2.0\frameworks\proj ects\framework\src\mx\core\UIComponent.as:5902] at mx.managers::LayoutManager/validateSize()[C:\autobuild\3.2.0\framework s\projects\framework\src\mx\managers\LayoutManager.as:579] at mx.managers::LayoutManager/doPhasedInstantiation()[C:\autobuild\3.2.0\ frameworks\projects\framework\src\mx\managers\LayoutManager.as:692] at Function/http://adobe.com/AS3/2006/builtin::apply() at mx.core::UIComponent/callLaterDispatcher2()[C:\autobuild\3.2.0\framewo rks\projects\framework\src\mx\core\UIComponent.as:8628] at mx.core::UIComponent/callLaterDispatcher()[C:\autobuild\3.2.0\framewor ks\projects\framework\src\mx\core\UIComponent.as:8568]