The left-hand side of an assignment must be a vari

[mhbashar1]

I have a field $F{SUM(total)} and a variable-$V{grand_total}.I want to assign a value to this field.I did the following in the expression editor of the field.

$V{grand_total}=$F{SUM(total)}

But it gives the error-The left-hand side of an assignment must be a variable value = (java.lang.Double)(((java.lang.String)variable_total.getValue())=((java.lang.Double)field_SUM40total_price41.getValue()));//$JR_EXPR_ID=10$

 

How to do it.At the same time,I want to show the value in that Field.