AdobeHCM P&F-Able to fill positions dropdown,unable to display values-EP3

Question

All,
I am able to populate the positions in drop down . I am seeing the all the positions, now when my form load I have to select one position and populate the rest of the DISPLAY values based on position. E.g. Company code, text , job key , job text . I have generic service which have all the fields . I added them on my form , but when I am choosing position from dropdown , nothing is populating .. I`ve used operation "GET_COMPANY_CODE_FOR_POSITION" . Any clue why ?
I exactly did the following , I am calling script event USER_EVENT_CHECK on CHECK .
But nothing is coming up .
Note : I donu2019t have any button , all I have is dropdown for positions
Re: HCM forms and Processes - Adobe
Please Advice.
Thanks,
Khan

Answer 1

Still NOT WORKING ...........!!!
Yes , it was easy and a smart way to trigger event .  I always knew you are smart guy
Here is what I`ve done
1- Populate dropdown for position via standard service "S_MGRS_POSITIONS" , bind this with SAP_PA with the same name I0001_PLANS.
2- Yaaaay! I can see the position in dropdown great -- Next step
3- Based on the position selected from drop down , I have populate and display 12 fields with their text from OM side .
4- I have created a generic service "ZS_POS_ATTRIBUTES" , import all the fields with their names e.g company code,job key , org unit , cost center , etc etc .. Including "effective date" .
5 - Per you reply I have drop button from ISR library which created all code for me and I commented the script for visible & invisible on FORMREADY. ( Able to hide button )
6- Copy mouse down / click ISR code  and plug that in on change EVENT of my dropdown
//Set ISR_EVENT for BAdI processing in backend
$record.CONTROL_PARAM.ISR_EVENT = "USER_EVENT_CHECK"
//Trigger call to backend for BAdI user command processing
ContainerFoundation_JS.SendMessageToContainer(event.target, "submit", "", "", "", "");
7- I have a user event called "USER_EVENT_CHECK "  which have all the fields for display including Action , effective date ( thanks a lot for your blog ) help  me a lot  to understand USER EVENT
8 - Now When I am loading my form via MSS  After picking position , it is not doing any thing ( I also put break point for my custom back end service , but it is not stopping at all )
9 - Humm, I thought , lets execute HRASR_TEST_PROCESS to make sure it is populating position F4_HELP value. Guess what , after hitting "F8" Execute , I didnu2019t see any positions F4 , but the moment  I clicked "CHECK" , it not only triggers my custom backend service but also come back with positions . I choose one position out of 7 positions and it again went to debugging mode .
Why I am unable to see the values for the slected positions 
Please advice .