Problems with 2 contitions (text comparison)

Hi,

I am having problems with performing an action (send e-mail) if 2 conditions (text comparison) are met only (in conjunction with Profile 2). I have tried the search option but didn't find a similar issue.

I want to send out a confirmation mail to a user in case he selects a certain option in a field of his profile 2 (taxonomy reference field). So I use the following which works nicely and as expected:

Event: After updating an existing profile
Condition: Text comparison updated profile (text starts with B, which is the term name)
Action: Send an e-mail to a certain address.

Since I want this very e-mail to be sent out once only and not over and over again every time the user updates other parts of his profile, I added a second condition which is basically the same as the first one with the addition that it does refer to the unchanged profile and is being set to 'negate'.

With this construction I was hoping that the mail would only be sent out in case the field in question has actually been changed. However, it does not work at all. The action won't be performed at all any more:

Event: After updating an existing profile
Condition: NOT Text comparison unchanged profile (text starts with B, which is the term name)
Condition: Text comparison updated profile (text starts with B, which is the term name)
Action: Send an e-mail to a certain address.

I have also tried the other way round with no luck:

Event: After updating an existing profile
Condition: Text comparison unchanged profile (text starts with A, which is the term name)
Condition: Text comparison updated profile (text starts with B, which is the term name)
Action: Send an e-mail to a certain address.

I have tried many different ways to achieve this. But it seems that as soon as I add a(ny) 2nd condition, no action is being performed at all, no matter whether the conditions are met or not.

Is there something I am doing wrong? Or is there a different way of performing an action only in case there actually has been a change in the field in question?

Thanks a lot in advance for your help!