Adding a new line to a .dat file from another simulation

Hello guys , i use dlmwrite function in my code

dlmwrite ('DFC1.dat',[anambe(:,1), anambe(:,6)],'delimiter','\t','precision',7);

and lets say i am runiing the code for another simulation still anambe(:,1) is the same for that case as well, i wanna keep the first and second columns from the first simulation but then if i run the code second code i want to add another line , in which case anambe(:,6) is different, so i want to add that line as a third column to .dat file.

dlmwrite ('DFC1.dat',anambe(:,3),'delimiter','\t','precision',7,'-append');

i tried that line but it is not working, can anyone help me please?