The requested font family is not available.

Hello guys, I'm having an error when try to replace a font using InDesign script like this:

function editTextFonts (openDoc, tfEditData, textFrame) {
    var lines = textFrame.lines
    var firstLine = lines.firstItem()
    var oldFont = firstLine.appliedFont

    if (!tfEditData.hasOwnProperty('font')) {
        return oldFont
    }

    var font = tfEditData.font
    var changeFont = oldFont.postscriptName.indexOf(font) === -1

    if (!font || !changeFont) {
        return oldFont
    }

    var newFont = findFontByPostscriptName(font, app.fonts)

    if (newFont === null || newFont.status !== FontStatus.INSTALLED) {
        return oldFont
    }

    for (var i = 0; i < lines.length; i++) {
        var line = lines[i]
        line.appliedFont = newFont.postscriptName
    }

When tries to assign newFont.postscriptName in appliedFont I got the error: The requested font family is not available. I have checked and the font is properly installed, even the variable newFont has the status INSTALLED. Any help with this will be really appreciated