VERIFIED SOLUTION i

Determining why some letter/flat mail is not receiving the DSCF discount, when it is being entered at the SCF within MailStream Plus

Product Affected:  MailStream Plus™
1)
One reason is if the mail is in a mixed-level tray.
Per the Domestic Mail Manual (DMM) some of the requirements for getting the DSCF rate for letters is-
"246 4.2.1 Letters
Pieces in a mailing that meet the standards in 2.0 and 4.0 are eligible for DSCF prices under either 4.2.1a. or 4.2.1b. below:      
a.When deposited at a DSCF or USPS-designated facility, addressed for delivery within that SCF's service area, and:
  1.Placed in a tray labeled to that DSCF.            
  2.Placed in a tray labeled to a destination within the DSCF's service area. This includes trays labeled to an ADC or an AADC facility with the exact same service area as the DSCF." 
Mixed-level trays are not 'labeled to the SCF' in the sense meant.  Not in the way that, say, a 5-digit or 3-digit tray is.  
Mixed-level trays are the 'working' tray level, and as such are labelled to the SCF just because that is where the mail will be initially processed, not necessarily because the mail is to the SCF.  So that level tray's contents are not eligible for DSCF.

2) 
Another reason may be if the mail is in an ADC or AADC tray. 
The DMM reference 2. in the answer above says-
"Placed in a tray labeled to a destination within the DSCF's service area. This includes trays labeled to an ADC or an AADC facility with the exact same service area as the DSCF."
If the ADC or AADC does not have the exact same service area as the SCF, pieces in the ADC or AADC tray cannot get the discount.

3) 
Sometimes pieces in a 5-digit scheme tray or sack do not get the rates, if the pieces are from two different SCFs.  Here is one sample example from Labeling List L012, as-of August 2015.
Pieces to ZIP Codes 11096, 11690, 11691 all get schemed to 'Far Rockaway NY 11691'.
The problem is that 110xx ZIP Codes are part of SCF 110 Queens NY, where-as 116xx ZIP Codes are part of SCF 112 Brooklyn NY.

Say there is a tray of mail pieces to 11096.  
If the pieces are entered at SCF 110, and go into a tray labelled to 5-digit scheme 11691, then they do not meet the USPS requirement 1. given above-
"1.Placed in a tray labeled to that DSCF."
Because the tray is labelled to 11691, a part of SCF 112, not part of the entry point SCF 110.

Or, say the pieces are entered at SCF 112, and go into the 5-digit scheme tray to 11691.  Now the tray is labelled to the correct entry SCF, but the pieces do not meet the requirement of a. in the text above-
"addressed for delivery within that SCF's service area"
There is nothing that can be done in these situations to get those pieces the SCF discount.  It's just due to the way the schemes are.

4)
If palletizing the mail-  Beginning with MailStream Plus™ 8.3.2 in June 2016, the USPS clarified that the pallet must be labelled to the same facility or finer level.  So for mail entered at an SCF for example , the mail will not *normally* (but may in some allowed cases) get an SCF discount if it is on a less-fine level pallet, such as NDC or Mixed NDC.  
(See ALG PL parameter positions 36, 37, and 38 about making USPS-allowed undersized entry pallets.)
UPDATED:  March 15, 2019