Sql question

Hi Experts,
I have the following table
TmpPatBillingCodes:

TmpPatBillingCodesID Number
EffectiveFrom Date
End Date

FYI-The first Column is not unique, its linked to another record of this table.
there are multiple records with same TmpPatBillingCodesID but different Dates.
Now I need to get a count of TmpPatBillingCodesID  grouped by datediff from effectivefrom-end 30 days, 60 days, 90 days and 90+
One more thing, All records containing the same TmpPatBillingCodesID are counted as 1 regarding the dates, meaning I need to get the date difference between min(EffectiveFrom) and Max(End) grouped by TmpPatBillingCodesID.
I would appreciate your help with this.
I am posting the sql that I have tried in Access, however it gives me an error that aggregate function in group by clause..

SELECT Count(TmpPatBillingCodes.TmpPatBillingCodesID) AS CountOfTmpPatBillingCodesID, Switch(DateDiff("d",Min([effectivefrom]),Max([end]))<31,"1-30",DateDiff("d",Min([effectivefrom]),Max([end])) Between 31 And 60,"31-60",DateDiff("d",Min([effectivefrom]),Max([end])) Between 61 And 90,"61-90",DateDiff("d",Min([effectivefrom]),Max([end])) Between 91 And 180,"91-180",DateDiff("d",Min([effectivefrom]),Max([end])) Between 181 And 365,"181-365",DateDiff("d",Min([effectivefrom]),Max([end]))>365,"365+") AS Expr2
FROM TmpPatBillingCodes
WHERE (((TmpPatBillingCodes.End) Between #1/1/2012# And #12/31/2012#))
GROUP BY Switch(DateDiff("d",Min([effectivefrom]),Max([end]))<31,"1-30",DateDiff("d",Min([effectivefrom]),Max([end])) Between 31 And 60,"31-60",DateDiff("d",Min([effectivefrom]),Max([end])) Between 61 And 90,"61-90",DateDiff("d",Min([effectivefrom]),Max([end])) Between 91 And 180,"91-180",DateDiff("d",Min([effectivefrom]),Max([end])) Between 181 And 365,"181-365",DateDiff("d",Min([effectivefrom]),Max([end]))>365,"365+");

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I know it would be easier to get this done in separate queries, however since this is meant for a user to run it temporarily, I would prefer not to have to save queries therefore my goal here is to have this all in one query, so user can just copy and paste.

Thanks