If they are invisible mode, you can still see the last time they have been on the forum.
Click on one of the lasts posts they made.
On the left-hand side, click the number to the immediate right of "
iTrader." This is located right underneath the member's avatar, immediately below "vCash."
Even if they have zero trades, it will still take you to a new iTrader page. Click on the number, even if it is "0."
On the right-hand column of the iTrader page, there is the "
View Full Profile for" column.
The "
Last Activity" will show the last time the member was on the forum, even if they are in invisible mode.