hi  Now i have purchased DS 2020 pro- i can see this is very different than 2019 version.

can someone please tell me why i can not select the dimension to delete, i can see the selection has happened but it also gives away quickly? only way i am managing is using "Cut" function. also, sometime, when i select the line, it selects the line and deselect itself. this is really annoying..... thanks for your help... 

i have also tried "Pickfirst" to 1 and 0 but no luck.