Group By and Count with several conditions

give a try on following

prepare the target datatable with build datatable activity - dtResult
Columns: Group, Count

use an assign activity
left side: dtResult
right side:

(From d in dtData.AsEnumerable
Group d by k=d("ID").toString.Trim into grp=Group
let grs = (From g in grp
               Where CDate(g(1).toString).toString("dd.MM.yyyy").equals(g(4).toString)
               Where g(2).toString.Equals(g(5).toString)
               Where g(3).toString.Equals(g(6).toString)
               Select dr=g).toList
Let ra = new Object(){k,grs.Count}
Select dtResult.Rows.add(ra)).CopyToDataTable

also have a look here:

the non LINQ approach maybe also can help to better handle the different date formatings