Commented Unassigned: Not able to select all row of Datagrid [20736]

Can't able to select all row by Ctrl+A ,there are some rows which are missing from selection when i press Ctrl+A in datagrid.
Any suggestion
Comments: ** Comment from web user: ashu_avni **

I used your approach and commented portion of code to isolate Ctrl+A feature, but still facing same issue.
Should i also change in Datagrid and its supporting classes i.e.(DataGridRow ,DataGridTextColumn)?