Finding solution to "Missing ';' or closing parenthesis in function 'If' at position 640. (IES 10063)" in Webi

I am trying to build a dimension in webi to look up someone's 65th birthday to attach the appropriate retirement fund label for our pension company.

Replace did not work for more than 2 so I tried to use If. Having built it I am getting error of IES 10063 . I have checked that each part has a closing parenthesis, and tried breaking it down, but each time get the same error and am now stuck. Would anyone be able to suggest how to resolve this issue please?

= if([65 birthday]>01/07/2016;if([65 birthday]<30/06/2020;if([65 birthday]>01/07/2020;if([65 birthday]>30/06/2025;if([65 birthday]<01/07/2025;if([65 birthday]>30/06/2030;if([65 birthday]>01/07/2030;if([65 birthday]<30/06/2035;if([65 birthday]>01/07/2035;if([65 birthday]>30/06/2040;if([65 birthday]<01/07/2040;if([65 birthday]>30/06/2045;if([65 birthday]>01/07/2045;if([65 birthday]<30/06/2050;if([65 birthday]>01/07/2050;if([65 birthday]>30/06/2055;if([65 birthday]<01/07/2055;if([65 birthday]>30/06/2060;if([65 birthday]>01/07/2060;if([65 birthday]<30/06/2065;"BE13");"BE23");"BE33");"BE43");"BE53");"BE63");"BE73");"BE83");"BE93");"BE03")

Thanks Duncan