Fillable form with Save & Share button, works on a Windows desktop but doesn't work on iPad

I created a fillable PDF form (timesheet) with Clear, Print and Save & Share buttons.  The buttons work on PCs but not on iPad or iPhone.  This form is a timesheet for construction workers to use while out on the field.  How can I get this work?  I need the most simplest way possible for the client.  All of fields work on the form but not the buttons.