Does not solve dependence on gradle (Android Studio)

I'm trying to make an application that reads bar codes and for that I use the ZXing library, but when I synchronize the project it tells me not to solve the dependency. Does anyone have any idea why this happens?

The library that causes me problems is

implementation 'me.dm7.barcodescanner: zxing: 1.9.8'

My gradle is this:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.codigodebarras"
        minSdkVersion 21
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    implementation 'me.dm7.barcodescanner:zxing:1.9.8'
}

I add capture of error messages