How do I open the mine in Harvest Moon DS?

Question

In the manual it says to go to Carter's archaeological dig after my crops are collected, in the early hours of the evening, and he will meet me and ask me to break through a weak patch of wall with my hammer. I've been every day for about a week now, and he won't meet me, or ask me to break down the wall. I tried digging in the cave in the wall, but there are no steps down to the next level so I guess the mine is still closed.

Any ideas on how to get further?

Answer 1

Enter the dig after 9pm with your hammer equipped.  That will open the first mine.

After that, opening the other mines is simple.  Go to the bottom of the most recently opened mine and defeat all the enemies there.  The game will do something to let you know you succeeded. (It is different for each mine.)  The repeat the step above on entering after 9pm with your hammer equipped.

There are 4 mines total, but the first three are the most important.