Can't evaluate expression.
You typed an expression that has invalid syntax . For example, an operand or operator may be missing, you may have typed an invalid character or comma, or you may have typed text without enclosing it with quotation marks ( " ). Check the expression to make sure you typed it correctly.
You typed an expression that is too complex. For example, a numeric expression may contain too many complicated subexpressions. Try simplifying the expression by assigning some subexpressions to variables .