INDEX giving identical values for diferent rows with different information

i have information in a table basically :
1 2 3 4 5 6 7
month cost cost cost cost cost cost cost
month cost cost cost cost cost cost cost
month cost cost cost cost cost cost cost
month cost cost cost cost cost cost cost

im using a combo box on a different page which gives me a column number for my selection

my data table at the top is defined as 'cost' and the column number defined as 'selectedcell'

underneath im using =index(cost,selectedcell,A1)

which is returning

month month cost cost cost cost cost.....

i cant fingure out how to correct it?

any help would be fantastic

Thanks

Tom