array delay

I'd like to use a variable that takes the value of another variable from the last time step. The other variable happens to be an array. I use the equation:

oldarray==delay([array],1)

However, this produces the following:

Testing Equation field produced the following error: Your explicit intermediate result, [array], has brackets round it that would indicate an array of single values. However it actually stands for an array of arrays of single values so should appear as follows: [[array]].

I should mention that the array is within a population submodel.

Any tips?