Error reloading array using VLOOKUP

I am receiving a "subscript out of range" error in my VBA code when I am trying to upload a fixed array from a worksheet using VLOOKUP. This is part of a model that iterates through changes in a series of input values in a worksheet, uploads the revised values to an array, and then runs calculations within the VBA code on the array. My initial loading of the array works fine, but when I try to reload it I get the subscript error. I've tried changing the size of the static array, and using dynamic arrays, but neither have worked. Any suggestions?