Index: gradebook/tool/src/java/org/sakaiproject/tool/gradebook/jsf/CourseGradeConverter.java
===================================================================
--- gradebook/tool/src/java/org/sakaiproject/tool/gradebook/jsf/CourseGradeConverter.java	(revision 1069)
+++ gradebook/tool/src/java/org/sakaiproject/tool/gradebook/jsf/CourseGradeConverter.java	(working copy)
@@ -31,6 +31,7 @@
 import javax.faces.convert.Converter;
 import javax.faces.convert.ConverterException;
 
+import org.apache.commons.lang.StringUtils;
 import org.sakaiproject.tool.gradebook.GradeMapping;
 import org.sakaiproject.tool.gradebook.ui.GradebookBean;
 
@@ -50,7 +51,7 @@
 			GradeMapping mapping = gbb.getGradebookManager().getGradebook(gbb.getGradebookId()).getSelectedGradeMapping();
 
 			// Find the corresponding standardized form, if any.
-			standardizedGrade = mapping.standardizeInputGrade(value);
+			standardizedGrade = mapping.standardizeInputGrade(StringUtils.trimToEmpty(value));
 			if (standardizedGrade == null) {
 				throw new ConverterException(new FacesMessage(FacesUtil.getLocalizedString(context,
 					"org.sakaiproject.gradebook.tool.jsf.CourseGradeConverter.INVALID")));