From MSDN:
pwdLastSet: "The date and time that the password for this account was last changed. This value is stored as a large integer that represents the number of 100 nanosecond intervals since January 1, 1601 (UTC). If this value is set to 0 and the User-Account-Control attribute does not contain the UF_DONT_EXPIRE_PASSWD flag, then the user must set the password at the next logon."

If you want to define the parameter of 50 days ago, you need to get the cTime from 50 days ago, using an appropriate Epoch. Then multiply it by 1000 to get ms. Use that value in your query. Simple, eh?

 Code:
; Get today as cTime, subtract 50 days, convert back to Date string
$FiftyDaysAgo = TimeConvert(TimeConvert(@DATE) - (50 * 86400))
$dFDAvalue = 0.0  ; cast as double
; convert adjusted date back to cTime, using required epoch, then
; multiply by 1000 to get ms instead of seconds
$dFDAvalue = TimeConvert($FiftyDaysAgo, '1601/01/01') * 1000.0


Untested, but it should work. I have to wonder why they used that epoch value, since the calendar was adjusted by removing 12 days in Sept, 1752. Not sure if you'll have to adjust your initial adjustment by 12 or not!

Glenn
_________________________
Actually I am a Rocket Scientist! \:D