[fixes] compare variants in lower case
diff --git a/erpnext/controllers/item_variant.py b/erpnext/controllers/item_variant.py
index 3508277..0ea0734 100644
--- a/erpnext/controllers/item_variant.py
+++ b/erpnext/controllers/item_variant.py
@@ -32,15 +32,16 @@
 	attribute_values = {}
 	for t in frappe.get_all("Item Attribute Value", fields=["parent", "attribute_value"],
 		filters={"parent": ["in", args.keys()]}):
-		(attribute_values.setdefault(t.parent, [])).append(t.attribute_value)
+		
+		(attribute_values.setdefault(t.parent.lower(), [])).append(t.attribute_value)
 
-	numeric_attributes = frappe._dict((t.attribute, t) for t in \
+	numeric_attributes = frappe._dict((t.attribute.lower(), t) for t in \
 		frappe.db.sql("""select attribute, from_range, to_range, increment from `tabItem Variant Attribute`
 		where parent = %s and numeric_values=1""", (item), as_dict=1))
-
+		
 	for attribute, value in args.items():
-		if attribute in numeric_attributes:
-			numeric_attribute = numeric_attributes[attribute]
+		if attribute.lower() in numeric_attributes:
+			numeric_attribute = numeric_attributes[attribute.lower()]
 
 			from_range = numeric_attribute.from_range
 			to_range = numeric_attribute.to_range
@@ -60,8 +61,8 @@
 			if not (is_in_range and is_incremental):
 				frappe.throw(_("Value for Attribute {0} must be within the range of {1} to {2} in the increments of {3}")\
 					.format(attribute, from_range, to_range, increment), InvalidItemAttributeValueError)
-
-		elif value not in attribute_values.get(attribute, []):
+		
+		elif value not in attribute_values.get(attribute.lower(), []):
 			frappe.throw(_("Value {0} for Attribute {1} does not exist in the list of valid Item Attribute Values").format(
 				value, attribute))