create a cascading dropdown !

hi everybody,

i need your help for this issue

i created two dropdown components one for material name and the second for the month of the billing document And like Events :

in the On Startup :

in the On Select of the Material dropdown :

But the problem that there is no filtre ! all the items of DS_1 appeare ! when i change the Matrial !

please take a look for this issue and help me to find a solution.

Have a great day

@Zoldek