Base Form info isn't save properly

I have a txt field, where I enter 10 digits, once field changed (because just inputed 10 digits) it calls a function to make my number format as phone number format and display it back…up to this point all are good, but if I click on the SAVE to capture this new good looking Phone format, it saves as straight numbers…WHY? Please help!!!

Example: I input 8185551212
Form Display Return by Function is: (818) 555-1212 [At this point SAVE button is BOLD]
I Click on SAVE, my saved info will be original input 8185551212

So far only way to get around for me is after return back from function, I go back to the field and delete last number and retype to indicate this field has been modified than it works, it will save the new format…So I need to know code to make a field to be recognized as modified…! BTW my table field name(Phone_Home) and form field name is same (Phone_Home), I tried table and form field names different, no success.

Using LibreOffice Version: 4.1.2.3
Build ID: 40b2d7fde7e8d2d7bc5a449dc65df4d08a7dd38

Thanks in advance for your kind help