CodingForums.com - XML validation with internal DTD

hi guys im very very new to XML and DTD's im trying to work through a work sheet and i have to validate my XML file which includes an internal DTD

the worksheet wanted me to create a DTD and should assume that all occurring attributes are mandatory, have i done this right? and can you please help me fix the error thank you

below is the validation error what does this mean:

1 ERROR FOUND:

26: 14 The content of element type "teaching" must match "(course)".

XML document:

Code:

1 <?xml version="1.0" ?>

2 <!DOCTYPE lecturers [

3 <!ELEMENT lecturers (lecturer)>

4 <!ELEMENT lecturer (name)>

5 <!ELEMENT name (teaching, research)>

6 <!ELEMENT teaching (course)>

7

8 <!ATTLIST name title CDATA #REQUIRED>

9 <!ATTLIST name first CDATA #REQUIRED>

10 <!ATTLIST name last CDATA #REQUIRED>

11

12 <!ELEMENT course (#PCDATA)>

13 <!ATTLIST course code CDATA #REQUIRED>

14

15 <!ELEMENT research (#PCDATA)>

16

17 ]>

18 <lecturers>

19 <lecturer>

20 <name title="Professor" first="Peter" last="Quirk">

21 <teaching>

22 <course code="CO3070">XML and the Web</course>

23 <course code="CO3300">

24 Web Server Architectures

25 </course>

26 </teaching>

27 <research>

28 The application of Web protocols to Biology

29 </research>

30 </name>

31 </lecturer>

32 </lecturers>

SOLVED i SOLVED IT AFTER 6HOURS if any one else is stuck on this you will need to add * within your parent element of your child which the error is caused for example <!ELEMENT teaching (course)> this will translate to <!ELEMENT teaching (course*)>