exec-maven plugin error when executing with mvn clean verify

Question

I get the below error when executing postman tests using exec Maven plugin. What am I doing wrong? I am fairly new to this, so, any help would be welcomed.

I run it with 'mvn clean verify'

Error:-

Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:exec (merge) on project ihtests: Command execution failed.

Plugin:-

<build>
            <plugins>
                        <plugin>
                            <groupId>org.codehaus.mojo</groupId>
                            <artifactId>exec-maven-plugin</artifactId>
                            <version>1.6.0</version>
                            <configuration>
                                <workingDirectory>.</workingDirectory>
                            </configuration>
                            <executions>
                                <execution>
                                    <id>merge</id>
                                    <phase>integration-test</phase>
                                    <goals>
                                        <goal>exec</goal>
                                    </goals>
                                    <configuration>
                                        <executable>
                                            /node_modules/newman/bin/newman.js
                                        </executable>
                                        <arguments>
                                            npm shipment-tests
                                        </arguments>
                                    </configuration>
                                </execution>
                            </executions>
                        </plugin>
            </plugins>
        </build>