Forum:Could not activate Stardust Dragon's effect

I was playing Yu-Gi-Oh! 5D's Duel Transer. Here was the field.

Me: Stardust Dragon Opponent: All-Out Attacks

Opponent's Turn: Activates The Shallow Grave. He selects Cyber Jar while I select Slate Warrior. Both monsters are Special Summoned to the field in face-down Defense Position. Due to the effect of All-Out Attacks, both monsters are flipped into face-up Attack Position. Cyber Jar activated and then Slate Warrior activated, starting a Chain. Cyber Jar was Chain Link 1, and Slate Warrior was Chain Link 2.So I tried to hold the A button to see if I could activate Stardust Dragon to negate the Cyber Jar but I couldn't. Why is this so?