Two drop-down list with filter

[mohd.documents]

Hi,
I mad two BO one for State and the other for City, I made the relationship and everything is working fine.
I created a customer BO and I want to put two fields to select State & City (Dropdown), the City fields will only show cities related to selected state, I tried everything and nothing work & I couldn't find any example in video tutorials
Appreciate if you could help me. Thanks

[aware_support]

There is a video tutorial about cascading drop downs. Please watch it.