Mis-Matched number of rows inserted in a table

Hi Guys,

DB=10.2.0.4

OS = RHEL AS 4, 32 bit

The following query returns ..1940782  rows for 'YESTERDAY'.

SQL> Select COUNT(*) MessageCount, trunc(sysdate -1) DAY from DeviceTravelStatusHistory dtsh

where dtsh.locationtime >= to_date(to_char(sysdate-1, 'YYYY-MM-DD'), 'YYYY-MM-DD');  2

MESSAGECOUNT DAY

------------ ---------

     1940782 31-JUL-12

But, When I tried to insert these rows into another temporary table, it shows only - 17023 rows created. Here is the insert query im using..

insert /*+ APPEND */ into RPTDBA.MESSAGE_METRICS(DEVICEINSTANCEGUID,AVLMSGCOUNT,DAY)

Select dtsh.deviceinstanceguid, COUNT(*) MessageCount, trunc(sysdate -1) DAY from DeviceTravelStatusHistory dtsh 

where dtsh.locationtime >= to_date(to_char(sysdate-1, 'YYYY-MM-DD'), 'YYYY-MM-DD') group by dtsh.deviceinstanceguid;