Error printing data to a text file

Hi everyone,

I have been working on a script for quite a while now and I am unable to print data to a text file.

I am working with two different multi-sphere bodies. I need to know the position, velocity, forces.... on the Centre of Mass and have this data printed in a text file (csv, txt, dat...). For this I am using the next work flow:

1.- Compute command:

#-------Define Compute to Calculate the Properties of Individual Multi-sphere Bodies (clumps)------#

compute bid all rigid property id_multisphere #body id (1 value)
compute btype all rigid property clumptype #M-sphere type as defined in fix paticleteplate/multisphere (1 value)
compute xcm all rigid property xcm #body position (based on CoM) (3 values)
compute vel all rigid property vcm #body velocity (based on CoM) (3 values)
compute fcm all rigid property fcm #fbody force (based on CoM) (3 values)
compute quat all rigid property quat #body quaternion (based on CoM) (4 values)
compute bmass all rigid property masstotal #body mass (1 value)

2.- Define the variable, as follows:

#---------------------------------Multisphere Compute Variable-------------------------------------#

variable com1 equal c_xcm[1]
variable com2 equal c_xcm[2]
variable com3 equal c_xcm[3]

3.- Dump the data:

#----------------------------------Dump Multi-sphere Properties------------------------------------#

dump rigids all local 1000 post/rigids*.dump c_bid c_btype c_massms c_xcm[1] c_xcm[2] c_xcm[3] c_quat[1] c_quat[2] c_quat[3] c_quat[4] c_vel[1] c_vel[2] c_vel[3] c_fcm[1] c_fcm[2] c_fcm[3]

It works: I can open the dump file using a text editor, however LPP does not work on this files so paraview cannot read the data.

4.- Printing the results to a text file:
#----------------------------------Print Variables to Text File----------------------------------------#

fix clump_1 all print 1000 "${c_com1}, ${c_com2}, ${c_com3}" title "X_Positon,Y_Positon,Z_Positon" file post/outputP1.csv screen no

I get this:
ERROR on proc 0: Substitution for illegal variable

I also tried to print this variable using therm_style:

#-----------------------------------------Output Settings-------------------------------------------#

fix ts all check/timestep/gran 1000 0.1 0.1
thermo_style custom step time atoms ke f_ts[1] f_ts[2] c_xcm[1] c_xcm[2] c_xcm[3]

It does not work.
ERROR: Thermo compute does not compute vector

I have tried a lot of different possibilities with no success.

I know that the problem I am having is related to the type of variable I am trying to print. I am aware that there are three types of variable, (global, per-atom & local), I also know than these are local variable. I was able to print some data using the command fix ave/histogram as I read this command can print local variables but the information I obtained was confusing to me.

Could some one point me in the right direction???

I attached the script I am working on so you can have the whole picture.

Thanks!!!