Compare-Object does not work properly

good day all,

i trying find change in personnel list monthly. personnel data being saved csv files on first , last day of month. after trying find difference between 2 csv file below cmdlet;

$a = import-csv c:\old_prs.csv
$b = import-csv c:\new_prs.csv

$result1 = compare-object $a $b -property logonname -passthru |select "name;logonname;mail;department" | export-csv c:\result.csv -notypeinformation

note: if use "select inputobject" instead of " select "name;logonname;mail;department" " , program write "inputobject" cell a1 of "result.csv" file, nothing else. 

both csv files has same columns "name;logonname;mail;department"

old_prs.csv below;

name	logonname	mail	department
name1	logonname1	mail1	dp1
name2	logonname2	mail2	dp2
name3	logonname3	mail3	dp3
name4	logonname4	mail4	dp4
name5	logonname5	mail5	dp5
name6	logonname6	mail6	dp6
name7	logonname7	mail7	dp7
name8	logonname8	mail8	dp8
name9	logonname9	mail9	dp9

new_prs.csv below;

name	logonname	mail	department
name1	logonname1	mail1	dp1
name2	logonname2	mail2	dp2
name2.5	logonname2.5	mail2.5	dp6
name3	logonname3	mail3	dp3
name4	logonname4	mail4	dp4
name5	logonname5	mail5	dp5
name6	logonname6	mail6	dp6
name7	logonname7	mail7	dp7
name8	logonname8	mail8	dp8
name9	logonname9	mail9	dp9
name10	logonname10	mail10	dp10
name11	logonname11	mail11	dp11
name12	logonname12	mail12	dp12
name13	logonname13	mail13	dp13

result below;

name	logonname	mail	department
name9	logonname9	mail9	dp9
name10	logonname10	mail10	dp10
name11	logonname11	mail11	dp11
name12	logonname12	mail12	dp12
name13	logonname13	mail13	dp13

result showing "name9" differen records exist in both old , new csv file

also, "name2.5" exist in new csv file not show difference.

any 1 or suggest solve problem?

best regards

ugur

$a = import-csv c:\old_prs.csv -delimeter ";" $b = import-csv c:\new_prs.csv -delimeter ";"   $result = compare-object $a $b -property logonname -passthru |select name,logonname,mail,department   $result | export-csv c:\result.csv -notypeinformation

Windows Server  >  Windows PowerShell