Hi,
I think the connection string name you have given as different in web.config
Connection string in your web.config should look like this....
<add name="mywork_str" connectionstring="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;User ID=mywork-PC;Initial Catalog=homework;Data Source=myDB" />
Otherwise change the name of the connection string that matches the string that you have gave in server side code(mywork_str).
I hope this helps you a bit.
Regards,
RK