FOR iterator subsystem in Simulink

I have a simulink model which has to do the following: In1 input would take in a vector of 3 element input (this will be time varying but for initial development/testing purposes I have used a constant [1 3 6]) and In2 is a constant matrix of 6x3 size whose value is X =

     1     4     6
     1     4     5
     1     3     6
     0     0     0
     2     3     5
     3     5     7
The simulink model should output the corresponding index (1 based index) of [1 3 6] in X (which should be 3).
When I simulate this model I am able to see value '3' at every loop (10 ms loop) with a scope inside the FOR subsystem. But when I  
scope this output outside the FOR subsystem, it always displays '0' and never equal to '3'. I am not able understand this behavior.
Please help!

[dpb]

italic I am not able understand this behavior.

Nor can we w/o seeing what you did...

I don't know Simulink at all, but is there not an interpolation/lookup block you could use directly w/o an explicit FOR...END loop?

If not, could write s-function and use intersect()

NB you'll need to always have an exact input match--maybe that's the problem in the simulation?