Siesta can not read variable

I am using pageUrl config on testing file several times. Therefore created a variable to keep test files through DRY coding;

var localApp = 'http://localhost:1841/app/';

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The thing when i'm using this variable in harness within pageUrl config getting this error;

HTTP ERROR 404 - Problem accessing /app/test/Siesta/localApp. Reason: Not Found

Somehow when I am using this variable with hostPageUrl it works very well. What exactly i am doing wrong here?