printer job monitoring problem

[sengkok]

hi,

i have written a printer job monitoring program as the code shown below , a
timer is used to call this function every second . i have a network printer
tat attached to my pc. i facing a problems that some time the program can
detect the print job but some how most of the time it cant detect any printer
job while actually the printing some documents .
any one has facing this problem before ? or any suggestion for me.
(i find out that most of the time when i print document from the internet
explorer , my program cant detect any print job)
beside using WMI , what others methods i can use to detect the print job ?

public void GetPrintJobsCollection()
{
string f_SearchQuery = "SELECT * FROM Win32_PrintJob";
ManagementObjectSearcher f_SearchPrintJobs =
new ManagementObjectSearcher(f_SearchQuery);
ManagementObjectCollection f_PrntJobCollection = f_SearchPrintJobs.Get();
foreach(ManagementObject f_PrntJob in f_PrntJobCollection)
{
MessageBox.Show ("Your Document(s) are Printing now") ;
m_JobID = f_PrntJob.Properties["JobId"].Value.ToString () ;
m_DocName = f_PrntJob.Properties["Document"].Value.ToString () ;
m_TotalPages = f_PrntJob.Properties["TotalPages"].Value.ToString () ;
m_PrinterQueue[m_PrintQCount] = m_JobID ;
if (Convert.ToDouble (m_TotalPages) <= 0)
m_TotalPages = "1" ;
DeductPrintingValue (Convert.ToInt16(m_TotalPages)) ;
}