I'm trying to develop some custom modules for my site. I have followed both the "supersimple" tutorial and the www.codeproject.com/KB/custom-controls/Creating_A_DNNModule.aspx tutorial. Both work fine until I have to add the module to the page, at which point this error:

Unhandled error loading module.
DotNetNuke.Services.Exceptions.ModuleLoadException: Unhandled Error Adding Module to ContentPane ---> DotNetNuke.Services.Exceptions.ModuleLoadException: Error: Inventory is currently unavailable. ---> System.Web.HttpCompileException: External component has thrown an exception. at System.Web.Compilation.AssemblyBuilder.Compile() at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.Skins.Skin.InjectModule(Control objPane, ModuleInfo objModule, PortalSettings PortalSettings) --- End of inner exception stack trace --- at DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(String FriendlyMessage, PortalModuleBase ctrlModule, Exception exc, Boolean DisplayErrorMessage) at DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(PortalModuleBase ctrlModule, Exception exc, Boolean DisplayErrorMessage) at DotNetNuke.UI.Skins.Skin.InjectModule(Control objPane, ModuleInfo objModule, PortalSettings PortalSettings) --- End of inner exception stack trace ---

Any idea what could be causing this?