Progress doesn't support 2 dimensional arrays - Only 1 dimension allowed I am afraid.
There are a number of ways around this. Probably the simplest is to multiply the x and y values to create a product key that can be used to access the specific element.
e.g. a 4 by 4 array has 16 possible data points. to retrieve the value in x=2 y=1, you multiply (x - 1) by 4 (the number rows to skip) and add y.