Unable to turn null pointger to wall pointer

In PFC, when I am running code, I am getting the error as shown in figure.

Please help If anyone can.
Thank you,

Probably your wall.find command did not find an object, therefore returning a null pointer (nothing). That’s why the error occurs when trying to access some info of that non-existing wall object.
I can’t say why wall.find does not return the correct pointer. Maybe you have misspelled something or the range for the wall assignment is wrong etc.