java 7 application blocked for security failed to validate c

I'm trying to install this game for the first time, and I'm having a hard time doing so. I keep getting an error. The thing says
I tried this how to, and it didn't work. http://forum.wurmonline.com/index.php?/ ... te-solved/
The more info says.
application blocked for security
failed to validate certificate
the application will not be executed.
I tried this how to, and it didn't work. http://forum.wurmonline.com/index.php?/ ... te-solved/
The more info says.
java.io.IOException: Invalid keystore format
at sun.security.provider.JavaKeyStore.engineLoad(Unknown Source)
at sun.security.provider.JavaKeyStore$JKS.engineLoad(Unknown Source)
at java.security.KeyStore.load(Unknown Source)
at com.sun.deploy.security.RootCertStore$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.deploy.security.RootCertStore.loadCertStore(Unknown Source)
at com.sun.deploy.security.RootCertStore.load(Unknown Source)
at com.sun.deploy.security.RootCertStore.load(Unknown Source)
at com.sun.deploy.security.ImmutableCertStore.load(Unknown Source)
at com.sun.deploy.security.LazyRootStore.loadJREStore(Unknown Source)
at com.sun.deploy.security.LazyRootStore.getTrustAnchors(Unknown Source)
at com.sun.deploy.security.TrustDecider.getValidationState(Unknown Source)
at com.sun.deploy.security.TrustDecider.validateChain(Unknown Source)
at com.sun.deploy.security.TrustDecider.isAllPermissionGranted(Unknown Source)
at com.sun.javaws.security.AppPolicy.grantUnrestrictedAccess(Unknown Source)
at com.sun.javaws.security.JNLPSignedResourcesHelper.checkSignedResourcesHelper(Unknown Source)
at com.sun.javaws.security.JNLPSignedResourcesHelper.checkSignedResources(Unknown Source)
at com.sun.javaws.Launcher.prepareResources(Unknown Source)
at com.sun.javaws.Launcher.prepareAllResources(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.launch(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)