help with dynamic pull down menu

Hi...

i got some problem with dynamic pull down menu

im using offset and counta function

the problem is, the cell that im going to use for reference cell and data for pull down menu is a merge cell. The formula works but it only show a part of the data

the formula that i use is:

offset(B5:C5, 0, 0, 1, counta(5:5))

i got 6 data, 1 to 6 but at the drop down menu only show 1 to 3

please help me..