Code That Return Correct Number Of Record When Run Without Aggregate Function

I have sql code that returns the correct number of record when run without an aggregate function like count(myfield) and group by myfield. It always returns 86 row which is correct when Select DISTINCT is used. As, expected when DISTINCT is not used I get double the number if rows or 172. But when I count(myfield) and group by myfield the count is 172 and not 86. The strangest thing about this is that when I am grouping a set of items

Group 1

Group 2

Group 3

The other group sum up correctly while others don't. What can explain this? Here is the code.

Select DISTINCT ws.p4Districtnumber, ws.cycle, ws.worksetid, count(msi.MeterSessionInputKey) as ASND
from fcs.dbo.WorkSet as ws
left outer join fcs.dbo.WorkAssignment as wa
on ws.WorkSetID = wa.WorkSetID
left outer join fcs.dbo.MeterSessionInput as msi
on wa.worksetkey = msi.worksetkey

[code]....