I have the same problem. 

The syntax to reference a screen's object in a picture window is not working in WebUX: 

Set obIO=HMIRuntime.Screens("00_StartScreen.PW_Main_3:screenName").ScreenItems("IOField_TitleName")

obIO.OutputValue=itemText

this works in runtime but not in WebUX. 

How is it possible to make it work? 

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Split from Dynamic action into I/O field is not fully working in WebUX.

Solved: the referenced object must be on an existing screen, not on a screen that is being displayed by the current script.

Also, a more convenient syntax can be:

HMIRuntime.Screens("00_StartScreen.PW_Main_3:screenName").ScreenItems("IOField_TitleName").OutputValue=itemText 

 Thanks support.

Hello vcamp7

Which Version of WinCC do you use exactly?

Bye Murof