Scratch

OK, So I put instructions for my main character to move back into its previous position if it touches the colour black so, in effect, it acts like a wall. Then I put instructions for my character to go to the start of the maze if it touched Rocket1 (the enemy). Rocket1 is coloured black from below but not from above. When my character touched Rocket1 from above, my character went back to the start but when it touched Rocket1 from below then it didn't, my character just acted as if Rocket1 was a wall. Is there anything I could do to to stop this OTHER than changing the black to a different colour? (Because I have 8 different costumes for Rocket1)