about alv tree

Hello expert:

i copy the 'BCALV_TREE_DEMO' to generate my own program , then modify some change.

but when i run the new program, alv tree can not be initiated normally. there is no any node in left hierarchy. but after i click the expend subtree or collapse subtree, all of the node get display.

who could tell me why it occurs

Best Regards,

Kevin