Regarding formatting of fix print and ave/correlate output

Respected All,
I am trying to get a fix print output in particular format but not able to do so.
The output is all random.

The problem regarding formatting of fix print output is resolved.

Instead of
fix 6 part print 10 " {nstep} {v1} {v2} {v3} ${vel}" file vel_Ni3Fe_F100_1K_$a.txt &
screen “no” title “vx vy vz vel”

It should be {str1} {str2} …