ERRORsymbol:class UserTransaction(cannot find symbol)/package javax.mail.in

Hi people, I am trying to compile a web proyect in MyEclipse with Ant 1.6.2, but now it appears an error that says :

[javac] F:\...\Doc1.java:13: cannot find symbol

[javac] symbol : class UserTransaction

[javac] location: package javax.transaction

[javac] import javax.transaction.UserTransaction;

[javac] ^

and another one:

[javac] F:\...\Doc2.java:19: package javax.mail.internet does not exist

[javac] import javax.mail.i nternet.MimeMultipart;

[javac] ^

I'm using tomcat 5.5.23

Could anyone say to me why could this happen?I think that I am using all the libraries I need and so on..

Thank you very much!!

[690 byte] By [crisssa] at [2007-11-27 9:32:10]