Different purchase suggestions when calculating regenerative plan for a single item

Business Central/NAV User Forum
1

Hallo,

this problem is driving me crazy.

Here’s the scenario:

I have a database of 15,000+ items, but only few hundreds are items that are regularly manufactured/purchased/sold (but I need them all as they all are “live” items). Some of them are sourced via purchasing, some other via production order. Navision W1 5.0

I calculate the regenerative plan every month to generate a 3-month worth of purchase orders and a year-long purchase forecast plan. I have Sales Orders in the system covering a month, and then Blanket Sales Orders covering one year (for forecasting purposes with my supplier, although effectively the 2nd and 3rd month are purchase orders on Blanket Sales Orders).

I noticed that the suggested Purchase Order proposals generated by calculating the regenerative plan, change (in volume, number of lines, etc.) depending on wheter the “No.” field in the “Item” tab of the Calculating regenerative Plan is left A: blank or B: “*”. This without changing any other setting, I tried few times running the two options back to back.

Moreover, even when calculating the plan leaving No. ="*" (which at first seemed “better” in output than leaving the field blank), I noticed that some purchase order suggestions (which I would have expected) were not generated. BUT, when re-calculating the regenerative plan for a specific item “A” (No.=“A”), then the expected suggestion are actually generated ?? This not only for one isolated item, there are actually quite a few.

I’ve been then suggested to calculate first the MPS regenerative plan, and then the MRP regenerative plan. The things seemed to be improving (i.e. a certain level of purchase order suggestion are generated almost as expected), but nonetheless I still see some items for which purchase order proposal are underestimated when looking at the Sales and Blanket Sales Order in the systems.

I can’t understand why this is happening. Despite any setting of the item card, I would expect that the Regenerative Plan would be consistent when ran with the different method I listed above, but it does not seem tha case.

Is this some sort of known (not to me!) bug ?

Your precious help woul be very much appreciated. Thanks!!

2

do you make sure nothing is moving between 1st run and 2nd run?

  • like no posting or purchase receipt, no posting of consumption, transfer, output, shipment, adjustment, any inventory transaction?
  • writing new sales order, change status of prod. orders, change dates on SO/PO/Prod. Order, updating production forecast, and such as, that will change the requirement date / demand date?
  • posting of capacity (routing) in prod. order, replan / refresh prod. orders, deleting POs, deleting SOs?

are you working in single user database (for test) or in live environment with multi user logged into the system?

3

Hi Joe,

sorry for my late reply (been off till yesterday).

I am positive nothing moves between the runs. That was the first thing I checked when we spotted the issue. We are in multi user environment and users can be logged in during the MRP run, however nothing is done on sales/purchase/production orders (we are a very small team). If anything, maybe some actions can be done on the administrative side (invoicing, payroll, etc.) but I don’t see how this would be relevant.

I should remark the fact that we started noticing abnormalities that would lead us into material shortages. When checking (just checking, no changes) the sales/purchase/orders for the relevant item(s), it did not add up, some purchase suggestions were just missing, simple as that. If the regenerative planning worksheet was then re-run straight away for that/those specific item/s only, then the purchasing suggestions appeared. No changes on the items data and transactions, just the way that the plan was re-run for selected items only insetad of the full items list ??!!

4

Well, well…this is a bit unusual.

Are you using SKU’s? Are you using a filter on Locations? Do you have Reorder cycle? (Might cause some shortage if Reorder cycle, Lead time doesn’t fit in the date range). Other than that…hmm… When you are done with the regenerative plan, what’s your ouput? Planned orders and/or Firm Planned?

Did you check the “Order Tracking” for the items under/over Qty vs demand? Might give you some hints. Other than that, you DB might be corrupted but you would get an error message. Talking about error message, did you check “Stop on error” when you run the MPS/MRP?

Another thing you can do to check the integrity: Clear all entries in Requ. Worksheet and then check table 246. There should be no entries there.

Did you activate logging in NAV so that you can be sure no one’s changed anything?

5

Hallo Jacques,

Thanks very much for your support.

Regarding your questions:

No, we are not using SKUs.

We do use a filter on location; this one is our “MAIN” location where it all happens; the other location is “QUARANTINE” which is only used to park small amount or rejected material;

We do use both Reorder Cycle and Safety Lead time. These are both set in the item cards for all items, as 10D for the Reorder Cycle and 5D for the Safety Lead time. It might be useful to note that we run MRP every month having daily Firm Sale Order from now until 4W out, and after that we use fortnightly Blanket Sale Orders for a whole year ahead.

The regenerative plan suggests both planned and firmed planned. We usually firm up 9-10W starting from now.

We do not use the item tracking function; to be honest I’m not quite sure what you mean by that, as we never really used the function.

We do flag the option “Stop on error”, and no errors are generated when running MPS/MRP.

Finally, when talking about table 246 you got me completely lost!!

I hope this helps? Maybe there’s a lead on the reordering cycle matter?

Thanks,

Paolo