Code not working properly

[mar0000]

data want;
set have; 
by ID Date Sport; 
keep ID Type Sport Date EventID Defn; 
day = ifc(FIRST.Date, 'Y', 'N'); 
person = ifc(ID, 'Y', 'N'); 
spo = ifc(FIRST.Sport, 'Y', 'N'); 
if Type in (1,2) then do;
dd = intck('MONTH', lag(Date), Date,'C');
if dd=> 6 of FIRST.ID then Defn = 'Y';
else Defn = 'N'
end;
else if Type in (3,4) then do;
if person='Y' and day='Y' and spo='Y' then Defn='Y'
else Defn = 'N';
end;
run;

data have; 
ID Type Sport Date EventID; 
12 1 Baseball 06JUN2018 8779 
12 1 Baseball 20JUN2019 8452 
29 4 Skiing 12JAN2018 5683 
29 4 Snowboard 12JAN2018 5683 
08 3 Basketball 20MAR2019 1689 
58 2 Tennis 30AUG2017 2157

The data above is an example of my data. 

This code is almost working how I want it to, but not yet. INTCK is semi-working, and I'm not sure how to completely get it to work (it will say 'Y' for NOV 2011 and 'Y' for JULY 2013, but 'N' for JUNE 2012. Is there a way to fix this? I also want this to return 'Y' for types 3 and 4 if they're 1 day between each other (January 1st and 2nd) and it isn't doing this. How would I fix these?

[ChrisNZ]

You cannot use the lag() function inside a test.

lag() needs to update its stack by being called.

If it's called after a IF test, it's not always called and value fall out of sync,

Use something like

PREV_DATE= lag(Date);
if TYPE in (1,2) then do;
  DD = intck('month', PREV_DATE, DATE, 'C');