diff --git a/erpnext/projects/doctype/timesheet/timesheet.js b/erpnext/projects/doctype/timesheet/timesheet.js
index 43f5705..99ee2a2 100644
--- a/erpnext/projects/doctype/timesheet/timesheet.js
+++ b/erpnext/projects/doctype/timesheet/timesheet.js
@@ -39,7 +39,7 @@
 
 	refresh: function(frm) {
 		if(frm.doc.docstatus==1) {
-			if(frm.doc.per_billed < 100){
+			if(frm.doc.per_billed < 100 && frm.doc.total_billable_hours && frm.doc.total_billable_hours > frm.doc.total_billed_hours){
 				frm.add_custom_button(__("Make Sales Invoice"), function() { frm.trigger("make_invoice") },
 					"fa fa-file-alt");
 			}
diff --git a/erpnext/projects/doctype/timesheet/timesheet.py b/erpnext/projects/doctype/timesheet/timesheet.py
index 01552a5..8d339b9 100644
--- a/erpnext/projects/doctype/timesheet/timesheet.py
+++ b/erpnext/projects/doctype/timesheet/timesheet.py
@@ -310,16 +310,16 @@
 
 @frappe.whitelist()
 def get_timesheet_data(name, project):
+	data = None
 	if project and project!='':
 		data = get_projectwise_timesheet_data(project, name)
 	else:
 		data = frappe.get_all('Timesheet',
 			fields = ["(total_billable_amount - total_billed_amount) as billing_amt", "total_billable_hours as billing_hours"], filters = {'name': name})
-
 	return {
-		'billing_hours': data[0].billing_hours,
-		'billing_amount': data[0].billing_amt,
-		'timesheet_detail': data[0].name if project and project!= '' else None
+		'billing_hours': data[0].billing_hours if data else None,
+		'billing_amount': data[0].billing_amt if data else None,
+		'timesheet_detail': data[0].name if data and project and project!= '' else None
 	}
 
 @frappe.whitelist()
@@ -327,6 +327,12 @@
 	target = frappe.new_doc("Sales Invoice")
 	timesheet = frappe.get_doc('Timesheet', source_name)
 
+	if not timesheet.total_billable_hours:
+		frappe.throw(_("Invoice can't be made for zero billing hour"))
+
+	if timesheet.total_billable_hours == timesheet.total_billed_hours:
+		frappe.throw(_("Invoice already created for all billing hours"))
+
 	hours = flt(timesheet.total_billable_hours) - flt(timesheet.total_billed_hours)
 	billing_amount = flt(timesheet.total_billable_amount) - flt(timesheet.total_billed_amount)
 	billing_rate = billing_amount / hours