Error while creating second doctype for module

Hello everyone,

I am playing with frappe and trying to create some app.

I have created new app, created some modules on it.
Created one doctype fo module and everything was ok. After i tried to create second doctype (it have saved without error messages) for same module. After what when i press icon form desk to what module error apears. Maybe someone know what i am doing wrong?

Traceback (innermost last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/app.py”, line 51, in application
response = frappe.handler.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 62, in handle
execute_cmd(cmd)
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 85, in execute_cmd
ret = frappe.call(method, **frappe.form_dict)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 708, in call
return fn(*args, **newargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/moduleview.py”, line 13, in get
data = get_data(module)
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/moduleview.py”, line 37, in get_data
set_last_modified(data)
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/moduleview.py”, line 186, in set_last_modified
item[“last_modified”] = get_last_modified(item[“name”])
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/moduleview.py”, line 190, in get_last_modified
last_modified = frappe.get_all(doctype, fields=[“max(modified)”], as_list=True, limit_page_length=1)[0][0]
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 856, in get_all
return get_list(doctype, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 829, in get_list
return frappe.model.db_query.DatabaseQuery(doctype).execute(None, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 49, in execute
return self.build_and_run()
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 61, in build_and_run
return frappe.db.sql(query, as_dict=not self.as_list, debug=self.debug)
File “/home/frappe/frappe-bench/apps/frappe/frappe/database.py”, line 140, in sql
self._cursor.execute(query)
File “/home/frappe/frappe-bench/env/lib/python2.7/site-packages/MySQLdb/cursors.py”, line 205, in execute
self.errorhandler(self, exc, value)
File “/home/frappe/frappe-bench/env/lib/python2.7/site-packages/MySQLdb/connections.py”, line 36, in defaulterrorhandler
raise errorclass, errorvalue
OperationalError: (1054, “Unknown column ‘modified’ in ‘field list’”)

This is pretty strange.

Did you drop any fields from your database? Did you DocType creation go through alright.

modified is a standard field created by the doctype.

thanks for your replay.
i did not drop any DB table. I have deleted what doctype and created new one, now everything working. So what was the reason for what error i dont understand.