How can i use an RInterp To node with a ForEachLoop?

Im trying to animate 12 static meshes within a blueprint to replicate somthing like the iris of an old camera or the stargate from the TV show

This is what ive gotten so far http://i.imgur.com/0hahVeR.jpg

In the construction script ive got an array that gets all the static meshes, and a second array that gets all their relative rotations. In the event graph im using a for each loop to cycle through the array of meshes, get its rotation and add values to pitch and yaw.

What im TRYING to do is push this through an RInterp To node to make it animate between the starting position (provided by the GET node) to the final position (provided by the Make Rot node after adding values)

So far ive been unable to make this run properly. If i connect the Event Tick to the Set Relative Rotation node it produces an error when i trigger it in game:

LogArray:Warning: Attempted to get an item from array Rotations out of bounds [12/11]!
LogArray:Warning: Attempted to get an item from array IrisLeafs out of bounds [12/11]!
LogScript:Warning: Accessed None 'CallFunc_Array_Get_Item2'
    IrisDoor_C /Game/Maps/UEDPIE_0_SampleRoom.SampleRoom:PersistentLevel.IrisDoor_C_0
    Function /Game/Blueprints/IrisDoor.IrisDoor_C:ExecuteUbergraph_IrisDoor:01EE
PIE:Error: Error Accessed None 'CallFunc_Array_Get_Item2' from node Set Collision Enabled in blueprint IrisDoor

The same error occurs when i try using a timer between the loop and set relative rotation nodes

Ive had advice to try using custom functions and timers/delegates but am unsure how i would do this

As the code stands, when i call the event IrisToggle the iris leafs will move to the position given from the calculation in a single frame, they dont animate.

Any advice would be great