If statement, if the values of Column1 are different from multiples values, then

[Aydeedglz]

I am trying to create a formula where "if the values of Column1 are different from "value1", "value2", "value3", "value4", then "error" if not "ok"

Also there is blank category and spaces that seem like blank and I am trying to incloude them or find a way to ignore them

I have tried like this:

Validation =

Var VARIABLE1 = SELECTEDVALUE('TABLE1'[Classification])

Return

IF(TABLE1 <> "Value1" || "Value2" || "Value3" || "Value4" || "Value5" || " " || "blank", "Error, "Ok")

But is not working because in my table I only have those values ("Value1" || "Value2" || "Value3" || "Value4" || "Value5" || " " || "blank") and is showing error like if it has another value different from them

[vicky_]

You can try re-write the formula as the following:
IF(SELECTEDVALUE('TABLE1'[Classification]) in {"Value1", "Value2"...etc}, "Error", "OK")