Datapicker in a datagrid non updating.Advice needed

Question

Hi all I have a datagrid that is filled with and observablecollection Lets say I have 2 columns DataOfBirth (dataPicker) and Surname(textBox)

This is using a mvvm pattern and the grid is mapped to the collection mentioned above.

When changing the date or amending the surname it does not seem to pick up the changes?

I cannot post the code but I was wondering about some pointers?

Thanks a lot!