Solving Invalid signature in JNLP

I have this error each time i run my jnlp:

invalid SHA1 signature file digest for

I found some discussions about possible solutions:

http://stackoverflow.com/questions/8176166/invalid-sha1-signature-file-digest

http://stackoverflow.com/questions/11673707/java-web-start-jar-signing-issue

But he problem was still there. I solved the problem using plugin option (<unsignAlreadySignedJars>true</unsignAlreadySignedJars>) and removing previous signatures to avoid possible signature duplications:

  <plugin>
     <groupId>org.codehaus.mojo.webstart</groupId>
       <artifactId>webstart-maven-plugin</artifactId>
         <executions>
           <execution>
             <id>jnlp-building</id>
             <phase>package</phase>
               <goals>
                 <goal>jnlp</goal>
               </goals>
            </execution>
         </executions>
         <configuration>
           <!-- Include all the dependencies -->
           <excludeTransitive>false</excludeTransitive>
           <unsignAlreadySignedJars>true</unsignAlreadySignedJars>
           <verbose>true</verbose>
           <verifyjar>true</verifyjar>
           <!-- The path where the libraries are stored -->
           <libPath>lib</libPath>
           <jnlp>
             <inputTemplate>webstart/jnlp-template.vm</inputTemplate>
             <outputFile>ProteoLimsViewer.jnlp</outputFile>
             <mainClass>cu.edu.cigb.biocomp.proteolims.gui.ProteoLimsViewer</mainClass>
           </jnlp>
           <sign>
             <keystore>keystorefile</keystore>
             <alias>proteolimsviewer</alias>
             <storepass>password</storepass>
             <keypass>password</keypass>
             <keystoreConfig>
               <delete>false</delete>
               <gen>false</gen>
             </keystoreConfig>
           </sign>
              <!-- building process -->
              <pack200>false</pack200>
              <verbose>true</verbose>
         </configuration>
     </plugin>