Attribute error in custom app


I have created a custom doctype Sourcing request using custom app called developer. I want to create the sourcing request document from opportunity like work order being created from Production plan. I have given custom script as below,

refresh: function(frm) {
	frm.add_custom_button(__('New Sourcing Request'),
		cur_frm.cscript.create_sourcing_request, __('Create Sourcing Request'));
make_sourcing_request: function(frm) {{
		method: "developer.developer.doctype.sourcing_request.make_sourcing_request",
		freeze: true,
		frm: cur_frm,
		callback: function() {

When I am giving create sourcing request from Opportunity i am getting Attribute error,

I am not sure where is the exact error, i have given the right path , kindly help.

Thanks in advance!

kindly provide content of screenshot.
highlight the method make_sourcing_request

Please find the screenshot for

make sure the make_sourcing_request method is the first level method, not under the class definition. and also add the @frappe.whitelist() decorator above the method

Ok thanks for the info, i have added @frappe.whitelist(). Now its running but when i am reloading the page its showing directly the below message,

Its not getting created, am i missing something in python script