Handing in date is drawing very close and im losing my mind over this.

\begin{pmatrix}1 & 4 & 6\\3 & 9 & 1\\2 & 6 & 5\\4 & 4 & 9\end{pmatrix}

ive been asked to find the rref(M) which is confusing me because I just end up with:

\begin{pmatrix}1 & 0 & 0\\0 & 1 & 0\\0 & 0 & 1\\0 & 0 & 0\end{pmatrix}

which kind of makes sence to me as there are 3 variables so one of the rows has to be a linear combination of the others? but im then asked to find the kernal(M) which seems to me to be the zero vector?????

how confusing...