HLOOKUP Formula that needs to ajust depending on a selection from a drop down list

Hello,

I'm fairly new to LOOKUP formulas and was wodnering if its possible for the formula to be automatically adjusted depending on a selection from a drop down list.

I have attached the ful workbook as all the sheets are linked one way or another..

Firstly, on the "Cover_Sheet" i have used the formula =HLOOKUP($B$1,Margin_Table!$B$1:$S$64,4,0) from B4:B30 which works fine, but when copied to columns C and D it returns "#N/A". The same thing happens when I select a different month from the drop down in B1.

Secondly, the bottom section of the table (row 27 to 30) is returning "0" because of the issue above.

Is it because B1 is a merged cell?

I've scoured google and several forums to no avail! A popular subject that comes up is either nesting HLOOKUP and VLOOKUP or using INDEX-MATCH...something which exceeds my excel knowledge.


Hope you can help,
Tom