Insert row with default value

My first steps with HeidiSQL. Create a table with two columns. First integer with autoincrement and key (it would be nice, when the key generated automaticly) -> work Second integer with a default value 1.

Switch to DATA tab. Press the green ADD button A row with NULL for first column an 1 for second column appears. Change the value for the second column to 7. A little red triangle appears an I press SEND -> the row will be insert.

Press the green ADD button A new row with NULL for first column an 1 for second column appears. I dont change the default value for the second column. I press SEND, nothing happens.

I can not insert a row with default value?

If I changed the default value the row will be insert