Changing a countrol source based on a field

[NickDenyer]

ok try this:

=IIf(Nz([field1],0)=0,"",IIf(Nz([field2],0)=0,IIf(DateDiff("d",Date(),[field1]+30)>0,DateDiff("d",Date(),[field1]+30) & " days before approval","30 days target has elapsed"),iif(datediff("d",[field1],[field2])<=30,"30 days target achieved","30 days target has elapsed")))

arnelgp! You are a coding genius! This has worked in everyway I hoped! And I am sure you are relieved to finally be done with me!

I have added reputation and you thoroughly deserved it! Thank you very much for all of your kind help!