I need to ask a few questions first.
Are you designing a form to distribute via the web (HTML form) or via PDF? What type of action are you trying to add?
For web forms there are no "button actions".
If your workflow is to create a PDF form let me know and I can provide more details.
I would like to design a PDF form with a buttom action to check if some fields are populated.
Depending of values of these fields and choises made for combo-boxes open a Msgbox and enable other fields.
For my previous job I used LifeCycle but 'unfortunately' now I have only FormsCentral installed.
Thanks in advance for your help,
The type of functionality you are looking for isn't supported in FormsCentral PDFs. You can mark fields as Requried and those have to be filled before the form can be submitted, but it can't enable other fields in the PDF based on that.
LiveCycle Designer is still available if you've purchased Adobe Acrobat Pro XI - see this document: