When you want to find out the value of a list item, use the field from which the list column is sourced (displayed as the Source property of the Column).
The following example uses a tree column sourced from the #SURNAME field. This field is used to find out the value of surname for the current item in the tree and then to set the item with surname BROWN to bold
IF COND'#SURNAME *EQ BROWN'
SET COM(#TRVW_1.CURRENTITEM) BOLD(TRUE)