Custom Activity error

Getting a below exception:
While creating custom activity I’m getting below error.
Code:
using Numpy;
var x = np.array(new float[,] { { 0, 0 }, { 0, 1 }, { 1, 0 }, { 1, 1 } });

Exception:
An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)