Vlookup = #N/A

Hi,

I am using the following IF formula;

=IF(AND(I21>1,I21<2),VLOOKUP(A3+30,A21:G968,2,FALSE),"")

For most of the cells this work smoothly. However;
The lookupvalues in column A is dates. I do not have data for all the dates of the year, and therefore I get an error when the lookupdate + 30 days does not exist in my spreadsheet.

What I am trying to do, is get the "A3+30" in my formula to become some sort of count. That is to say, I would like the values in A33 to show, regardless if this is the date in A3 + 30 days.

Hope this explaination was good enough for someone to grasp my problem and are willing to guide me

(If not I can provide a sample sheet)

Gnoke