Error #1009 in advanceToComposeStartPosition()

Hello!

I get this error when I try to updateAllControllers:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at flashx.textLayout.compose::BaseCompose/advanceToComposeStartPosition()
at flashx.textLayout.compose::BaseCompose/composeTextFlow()
at flashx.textLayout.compose::ComposeState/composeTextFlow()
at flashx.textLayout.compose::StandardFlowComposer/http://ns.adobe.com/textLayout/internal/2008::callTheComposer()
at flashx.textLayout.compose::StandardFlowComposer/internalCompose()
at flashx.textLayout.compose::StandardFlowComposer/updateToController()
at flashx.textLayout.compose::StandardFlowComposer/updateAllControllers()

Does anybody know in what direction I need to seek to correct this problem?