diff --git a/server/AyaNova/biz/FilterSqlCriteriaBuilder.cs b/server/AyaNova/biz/FilterSqlCriteriaBuilder.cs
index f61278d3..48dac658 100644
--- a/server/AyaNova/biz/FilterSqlCriteriaBuilder.cs
+++ b/server/AyaNova/biz/FilterSqlCriteriaBuilder.cs
@@ -97,22 +97,22 @@ namespace AyaNova.Biz
                     case FilterComparisonOperator.Equality:
                         //no change on equals for nulls
                         break;
-                    case "GreaterThan":
+                    case FilterComparisonOperator.GreaterThan:
                         //no change on greater than for nulls
                         //(nulls are going to be assumed to be always at the
                         //less than end of the scale)
                         break;
-                    case "GreaterThanOrEqualTo":
+                    case FilterComparisonOperator.GreaterThanOrEqualTo:
                         //no change on greater than for nulls
                         //(nulls are going to be assumed to be always at the
                         //less than end of the scale)
                         break;
-                    case "LessThan":
+                    case FilterComparisonOperator.LessThan:
                         sb.Append("Is Null OR ");
                         sb.Append(sColumn);
                         sb.Append(" ");
                         break;
-                    case "LessThanOrEqualTo":
+                    case FilterComparisonOperator.LessThanOrEqualTo:
                         sb.Append("Is Null OR ");
                         sb.Append(sColumn);
                         sb.Append(" ");
@@ -156,25 +156,25 @@ namespace AyaNova.Biz
                                 sb.Append("'");
                                 break;
 
-                            case "GreaterThan":
+                            case FilterComparisonOperator.GreaterThan:
                                 sb.Append(">'");
                                 sb.Append(sValue);
                                 sb.Append("'");
                                 break;
 
-                            case "GreaterThanOrEqualTo":
+                            case FilterComparisonOperator.GreaterThanOrEqualTo:
                                 sb.Append(">='");
                                 sb.Append(sValue);
                                 sb.Append("'");
                                 break;
 
-                            case "LessThan":
+                            case FilterComparisonOperator.LessThan:
                                 sb.Append("<'");
                                 sb.Append(sValue);
                                 sb.Append("'");
                                 break;
 
-                            case "LessThanOrEqualTo":
+                            case FilterComparisonOperator.LessThanOrEqualTo:
                                 sb.Append("<='");
                                 sb.Append(sValue);
                                 sb.Append("'");
@@ -690,22 +690,22 @@ namespace AyaNova.Biz
 
                                         break;
 
-                                    case "GreaterThan":
+                                    case FilterComparisonOperator.GreaterThan:
                                         sb.Append(">'");
                                         sb.Append(sGreaterThanValue);
                                         sb.Append("'");
                                         break;
-                                    case "GreaterThanOrEqualTo":
+                                    case FilterComparisonOperator.GreaterThanOrEqualTo:
                                         sb.Append(">='");
                                         sb.Append(sLowEnd);
                                         sb.Append("'");
                                         break;
-                                    case "LessThan":
+                                    case FilterComparisonOperator.LessThan:
                                         sb.Append("<'");
                                         sb.Append(sLessThanValue);
                                         sb.Append("'");
                                         break;
-                                    case "LessThanOrEqualTo":
+                                    case FilterComparisonOperator.LessThanOrEqualTo:
                                         sb.Append("<='");
                                         sb.Append(sHighEnd);
                                         sb.Append("'");
@@ -783,19 +783,19 @@ namespace AyaNova.Biz
                                     sb.Append("=");
                                     sb.Append(sValue);
                                     break;
-                                case "GreaterThan":
+                                case FilterComparisonOperator.GreaterThan:
                                     sb.Append(">");
                                     sb.Append(sValue);
                                     break;
-                                case "GreaterThanOrEqualTo":
+                                case FilterComparisonOperator.GreaterThanOrEqualTo:
                                     sb.Append(">=");
                                     sb.Append(sValue);
                                     break;
-                                case "LessThan":
+                                case FilterComparisonOperator.LessThan:
                                     sb.Append("<");
                                     sb.Append(sValue);
                                     break;
-                                case "LessThanOrEqualTo":
+                                case FilterComparisonOperator.LessThanOrEqualTo:
                                     sb.Append("<=");
                                     sb.Append(sValue);
                                     break;