I installed the forum module and is perfectly visible but when I click on "General Discussion" (for example) I get this error:

Source

1687     *
1688     * @return bool Set to TRUE if the user is allowed to, to FALSE if they're
1689     * not
1690     */
1691    function canAttach() {
1692       return $this->CanAttachFiles ? true : false;
1693    }
1694
1695    function ForumHolderURLSegment() {
1696       trigger_error('Forum::ForumHolderURLSegment is deprecated. Please use Forum::ForumHolderLink() instead which works with nested URLs.', E_USER_WARNING);
1697       return $this->ForumHolderLink();
1698    }
1699
1700    /**
1701     * Get the forum holder's URL segment
1702     */

What's the problem?

Dear Willr, here the complete message:

Source
1687     *
1688     * @return bool Set to TRUE if the user is allowed to, to FALSE if they're
1689     * not
1690     */
1691    function canAttach() {
1692       return $this->CanAttachFiles ? true : false;
1693    }
1694
1695    function ForumHolderURLSegment() {
1696       trigger_error('Forum::ForumHolderURLSegment is deprecated. Please use Forum::ForumHolderLink() instead which works with nested URLs.', E_USER_WARNING);
1697       return $this->ForumHolderLink();
1698    }
1699
1700    /**
1701     * Get the forum holder's URL segment
1702     */
Trace
•trigger_error(Forum::ForumHolderURLSegment is deprecated. Please use Forum::ForumHolderLink() instead which works with nested URLs.,512)
Line 1696 of Forum.php
•Forum_Controller->ForumHolderURLSegment()
Line 369 of ViewableData.php
•ViewableData->obj(ForumHolderURLSegment,,,1,)
Line 411 of ViewableData.php
•ViewableData->cachedCall(ForumHolderURLSegment,)
Line 424 of ViewableData.php
•ViewableData->hasValue(ForumHolderURLSegment)
Line 133 of .cache.forum.templates.Layout.Forum.ss
•include(C:\Windows\Temp\silverstripe-cacheC--wamp-www-*******\.cache.forum.templates.Layout.Forum.ss)
Line 420 of SSViewer.php
•SSViewer->process(Forum_Controller,Zend_Cache_Frontend_Output)
Line 411 of SSViewer.php
•SSViewer->process(Forum_Controller)
Line 202 of Controller.php
•Controller->handleAction(SS_HTTPRequest)
Line 143 of RequestHandler.php
•RequestHandler->handleRequest(SS_HTTPRequest)
Line 147 of Controller.php
•Controller->handleRequest(SS_HTTPRequest)
Line 199 of ContentController.php
•ContentController->handleRequest(SS_HTTPRequest)
Line 184 of ContentController.php
•ContentController->handleRequest(SS_HTTPRequest)
Line 67 of ModelAsController.php
•ModelAsController->handleRequest(SS_HTTPRequest)
Line 282 of Director.php
•Director::handleRequest(SS_HTTPRequest,Session)
Line 125 of Director.php
•Director::direct(/forums/general-discussion/)
Line 127 of main.php

Where's the problem?