Formulas affecting Formulas?

Hiya,

On the attached sheet I have a page called 'Week' that shows dates. Previously I have been able to match those dates and generate a list with the following formula on page 'Formula'.

=IF(OR(E2=Week!$B$2,E2=Week!$B$3,E2=Week!$B$4,E2=Week!$B$5,E2=Week!$B$6,),COUNT(G$1:G1)+1,"")

For some reason it won't display anything and I'm wondering whether it's to do with the formula it's table it's reading from on page 'Intouch'.