Looking at the image you attached to that last reply, it appears that your code for handling the change to the Status field is not contained within any subroutine.
Your image shows the following:
(some items truncated for brevity)
Dim strTo
Dim strSubject
Dim strComment
If Bug_Fields("BG_STATUS").IsModified then
strTO = Bug_Fields("BG_RESPONSIBLE").Value
strSubject = "Defect Status ..."
strComment = "Defect Status ..."
TDConnection.sendmail strTo, strFrom, strSubject, strComment, NULL, "HTML"
Set TDConnection = Nothing
Msgbox "Mail Sent"
End If
Sub Bug_AfterPost
...Just before the "Sub Bug_AfterPost" declaration there is no "End Sub" statement to indicate the Status code was contained in some subroutine. That is bad.
So, please show all the code from the first Sub statement through the last End Sub statement that shows how you included the code for emailing both on a Status change and on an Assigned To change. Show us all the code in the scenario where it "doesn't work".