rostopic pub: "required argument is not a float" while sending Float32MultiArray.

edit

Hello,
I would like to run one of my robot's wheel with a ros command in a terminal.
The function I use need two parameters so I wanted to use Float32MultiArray.

My arduino code ressembles to the following one:

float x,y;
----------
/*callback*/
void cmd(const std_msgs::Float32MultiArray& array){
  x = a.data[0];  
  y = a.data[1];  
  motor1.run(x,y); }
----------
/*suscriber*/
ros::Subscriber<std_msgs::float32multiarray> sub("cmd", &cmd);

In a terminal, I type the following command:

rostopic pub /cmd std_msgs/Float32MultiArray "layout:
 dim:
 - label: "run"
 size: 2
 stride: 1
 data_offset:0
data:[100 100]" --once 

However, I have the following error:

[WARN] [..]: Inbound TCP/IP connection failed: <class 'struct.error'="">: 'required argument is not a float' when writing 'label: run
size: 2

Thank you in advance for your help.

Kindest regards,