Cannot resolve symbol within a Gradle script but resolving within source code

I am developing a gradle build script and I am trying to use an external library that I created.

I uploaded the library to a local repository both the jar and sources jar. Then I tried to use it within a gradle script, using the buildscript statement to define the dependency

buildscript {
    repositories {
        maven {
            name = 'repoLocal'
            url = "file://D:/Workspace/mvn_repo"
        }
    }
    dependencies {
        classpath 'it.zebco.alm:almproperties:1.3.0'
    }
}

Then within the build.gradle script I try to use the library classes

import it.zebco.alm.AlmProperties
AlmProperties ap = new AlmProperties()

which always gets me "Cannot resolve symbol" for AlmProperties references within the same script. If I run "gradle -b build.gradle", execution ends without errors. By the way, if I copy the AlmProperties source code to a buildSrc directory, Intellij Idea resolves the class correctly.

Moreover, if I specify

repositories {
    jcenter()
    maven {
        name = 'repoLocal'
        url = "file://D:/Workspace/mvn_repo"
    }
}


dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.4.12'
    compile 'it.zebco.alm:almproperties:1.3.0'
}

and I define a dummy.groovy file containing 

package dummy

import it.zebco.alm.AlmProperties
AlmProperties ap = new AlmProperties()

AlmProperties class is resolved correctly.

Standard suggestions (restart/resync/reimport the project) don't work.

Any other suggestions ?

Regards

Evelino Bomitali