How to check in column and if different prompt user and restrict users?

Currently, i have an column with an drop down i would like that for when user select different row if the user select in that column something not compatible it will prompt the user that this is not allow and restrict the user for adding in or typing in till they reselect the drop down, in vba

I have make an example Marco workbook where my category i have an drop down list, user are allow to select the same name however, 3G and 4D are not allow to be selected when 4D is selected, it will prompt the user that this is not allow and restrict the user for doing anything next, so how can i do this in VBA ?

Thanks it work perfectly of what i wanted where the user cant select the it
can i from this add on with using or ?

Originally Posted by Bernie Deitrick

That is a task better solved with a different technique.

Fill 4 cells in a column with 4D, 4O, 6A, 6B then select them, and name them something like "Group1"
Fill 6 cells in a column with 3G, 4A, 4B, 4C, 4H, 4K, 4P then select them, and name them something like "Group2"

Then have a cell - say, D1 - with Data Validation and the list option, with Group1,Group2 as the list

Then for all the other cells, use Data Validation with the list option, with =INDIRECT($D$1) as the source.

Then the data validation will do the work for you once you have select the group from the DV of D1.

I see what u mean but this is in 1 single drop down where in my business process where now currently is like in 1 column and if they choose the first is fine but if they choose the 2nd it check and prompt them

nice this will work too

Thanks