Trying to add effect on weapon, not working.

[Rilmarion]

https://imgur.com/a/IKPmr

The weapon and it's syntax is above. Basically want to make it so if Target of the dagger is Medium, the weapon should roll advantage on attack. So I target myself and roll, being a half-elf I am medium size. So I should rol with advantage, but only roll one d20. What am I doing wrong?

[Trenloe]

Assuming you're using the 5E ruleset? Please remember to indicate what ruleset you're using in future. Thanks.

1) You can't apply effects to a weapon - they need to be applied to the individual character in the combat tracker.
2) Try: IFT: size(medium); ADVATK applied to the character in the combat tracker.

This will be for all attacks done by that character, so you may need to ask the GM to remove/disable when not using the dagger, or ask the GM to enable the player effect removal extension so that players can add and remove as necessary: https://www.fantasygrounds.com/forums/showthread.php?23566-5E-Player-Effect-Removal-Extension

[Rilmarion]

Ah, thanks. That was the key, thought maybe it could be done to a weapon itself, but adding a power with duration of next action, it worked as intended.