Don't write the value in double quotes since the double quotes are not part of the value.
They mean, that the value is a string, not a number.
Unfortunately, if you just type 5277 into the condition this will be casted to a number and therfore the condition returns false (a string does not equal a number).
To solve this, either replace the left side of your condition with the expression int(Compose('Compose-Customer_Number')) or replace the right side of your condition with the expression string(5277)