Need Guidance

To a native speaker, the use of "shame" here is fine. However, it may leave a learner confused. He might think that it's shameful not to be able to attend.

"It's a shame (that) you won't be able to attend, but we do hope to see you at a more convenient time."

You could use "pity" instead of "shame", which would avoid the possible double meaning of "shameful".

Edwy

Even though "pity" can be substituted for "shame", it may also be misunderstood by a learner. One might think that if he doesn't attend, then he is to be pitied. But I have to admit that in this context, more people use "pity" than "shame".

Dear Teacher Eric,

Thank you very much for helping me in understanding the sentence.

I have seen the words "your goodself" being used in a formal letter writing but I can't find the word in dictionary. May I know what does the phrase mean? When and how to use it?

As three words, 'your good self' is a formally polite and somewhat dated way of saying 'you'. Where it appears now, it is often used mock-politely between familiars. I would suggest that you not overuse it, as it can sound rather stilted.