Combobox Values Depends On Cell Status?

I have a worksheet with three columns in it. the first column is the "channel column", the second column is the "status column"; which indicates the status of the channel column wheter it is active or not, the third column is the "circuit name" column which indicates the circuit name for each channel. now, the status of the channel depends on the value of the circuit name column.. if the cell in the circuit name column is blank, the status column has an if formula that automatically changes it to vacant status, otherwise active.

i added command buttons namely "active" and "vacant". this buttons correspons to active userform and vacant useform when clicked. in each userform there is a combobox. My problem is how would i fill the combobox in the active userform with the active channels only , and same in the vacant userform with vacant channels only. the comboboxes list should correspond to changes in the status column, that is if one channel gets an active status it would be deleted from the vacant userform and be added to the active userform