The generator matrix

 1  0  1  X  1  1  1  1  1  1  0  X  1  1
 0  1  X  1 X+1  1  0  X X+1  1  1  1  0  X

generates a code of length 14 over Z2[X]/(X^2) who´s minimum homogenous weight is 14.

Homogenous weight enumerator: w(x)=1x^0+12x^14+1x^16+2x^20

The gray image is a linear code over GF(2) with n=28, k=4 and d=14.
As d=14 is an upper bound for linear (28,4,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 4.
This code was found by Heurico 1.16 in 0.000329 seconds.