spinner "error message: bad arguments to is text empty?

I need some help with the following coding. I am trying an easy if --> then --> else solution. But regarding to the spinner it might not be easy as it seems. 

In my App solution it is not allowed to change the screen, if there is no item selected from spinner1, spinner4, spinner5 or spinner6. 

In my case, when no item is selcted there will an alert "Please select an item."

But it won`t work. In stead of my alert message the following error occurs.

It seems, that an item has to be selected, before another action can be done. Maybe some one has a better solution or an great idea.

Thanks in advanced.

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set the spinner selectionindex to 1 in Screen.Initialize (or to any other default value you like)

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Great! 

THX

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