4th Ed: do weapon modifiers stack with power modifiers?

[DragonOfUndeath]

im playing a rogue who uses throwing daggers and shurikan that add my DEX modifier to my roll against an opponents AC and all my powers also add DEX to my roll against opponents. do these stack or not? i can't find the rules for this in the players handbook

[Krazddndfreek]

No. They are two different powers/attacks. One is your basic ranged attack and the others are your rogue powers. So you only use your dex mod once.

[Kurald Galain]

im playing a rogue who uses throwing daggers and shurikan that add my DEX modifier to my roll against an opponents AC

Throwing daggers and shuriken do not add any modifiers to any attack roll (except if they're magical weapons, of course, in which case they add their enhancement bonus of e.g. +1).

A ranged basic attack will add your dex modifier. Most rogue powers will also add your dex modifier. But you can never simultaneously use a rogue power and a ranged basic attack, you have to pick one of them.

So no, you do not add your dex twice.