wlu: make sure the file name is not empty

org.eclipse.epf.export.msp.ui/src/org/eclipse/epf/export/msp/ui/wizards/ExportMSPWizard.java

diff --git a/org.eclipse.epf.export.msp.ui/src/org/eclipse/epf/export/msp/ui/wizards/ExportMSPWizard.java b/org.eclipse.epf.export.msp.ui/src/org/eclipse/epf/export/msp/ui/wizards/ExportMSPWizard.java
index 12380ff..e9e6eb8 100644
--- a/org.eclipse.epf.export.msp.ui/src/org/eclipse/epf/export/msp/ui/wizards/ExportMSPWizard.java
+++ b/org.eclipse.epf.export.msp.ui/src/org/eclipse/epf/export/msp/ui/wizards/ExportMSPWizard.java
@@ -172,7 +172,9 @@
 	 */
 	public boolean canFinish() {
 		if (wizardExtender != null) {
-			return wizardExtender.canFinish();
+			if (! wizardExtender.canFinish()) {
+				return false;
+			}
 		}
 		return getContainer().getCurrentPage() == selectExportDirPage
 				&& selectExportDirPage.isPageComplete();