How to make main beam angle in MATLAB and CST be the same?

Hi everyone, I am working on Active Electrically Scanned Antenna (AESA).
I got an array with 8x4 elements and fixed spacing.
My work focus on computing Weights (Amp and Phase) in MATLAB to steer the main beam and use CST to verify the main beam angle.
My problem is that the main beam angle in MATLAB and CST are significantly different with the same Weights.
I tried some way to model mutual coupling in MATLAB such as
+ Embedded element pattern
+ Get pattern (included coupling) of each element in CST to import to custom antenna element in MATLAB.
+ Get phase pattern of elements in CST and import to MATLAB.
But all of them cant work.
Therefore, is there any way to make patterns in MATLAB and CST be the same?
If you have any idea or experience of this problem, please give me some advice.
I hope my question is clear for you. Thank you for your time.