A. Restrictions on the Herd Growth routine
As you can see, the routine figures flows of animals in each class on yearly basis. Then the user needs to remember that this sometimes causes unexpected decrease in animal numbers, especially in animals with short production cycles such as sheep and goats. For example, if you set 0.5 for years in replacement stock, it means the number of replacements which become to be breeders in one year is nearly two times as much as the number of replacement stocks at any point in time. However, in the Herd Growth routine, a flow to the next class is always smaller than the size of the stock.
The user also needs to pay attention to the difference between results of the Herd Growth routine and that of the Demand Driven routine. When you use the size and composition of the herd shown in results of the Demand Driven routine for base year structure in the Herd Growth routine, production amount of meat in the Herd Growth routine is not same as that in the Demand Driven routine. There are some reasons; a) a part of replacement stock produces meat in the Demand Driven routine, however, does not in the Herd Growth routine, b) as mentioned above, animals are slaughtered once a year in the Herd Growth routine.
B. Do not use LDPS2 to make projections aimed at forecasting exact herd size and production values.
Animal production systems are complex and subject to a wide range of factors, most of which the planner have no control, and often no data describing their behavior.
C. LDPS has great value in pointing out inconsistencies in existing data, but is limited in identifying which data are incorrect.
While using LDPS2, you may notice some strange behavior or awkward results. This may be caused by inconsistent data sets. This happens when incompatible or contradictory data are used in a same set. LDPS2 may show you these inconsistencies, but pinpointing the wrong data is another cup of tea.
If you are faced with such a problem, go through you data sets and try to find suspicious data values or parameter levels. This is the only way out of there.
D. LDPS never gives the `right' answer.
LDPS2 has a mathematical behavior. The number of factors taken into account is limited, and the equation sets are a simplified image of reality. Always keep these facts in mind when using the spreadsheet and when interpreting the results. These results should not be used directly to implement or influence real policy. They should be put to the test by experienced officers in the field of animal production.
Here is a list of the problems you are most likely to encounter when using LDPS2. The left column of the following table spells the problem, and the right column shows a possible cause and solutions.
| Problem | Cause and solution |
| 1) Installing LDPS2 | |
| LDPS2 will not install on your hard disk. | You may need more free space ( at least 5 meg) |
| Message "No program is associated with this file". | Either you don't have Excel installed, or the file extension ".XLS" is not associated with Excel. Find Excel, open it and open the file with the "FILE_OPEN" menu. |
| Message "This program requires Microsoft Windows" | You are trying to run Excel from the DOS prompt. Start Windows first, then run Excel. |
| Message "File ldps2.xls already exists. Overwrite file?" | You have already installed LDPS2 are attempting to install it over again. Check the version already installed. If you do want to re-install it, just answer � YES � when the message shown at left is displayed. |
| 2) Using LDPS2 | |
| Message "Object does not support property". | You may be using an old version of Excel. Try at least version 5 |
| Macro error at run time. | Macros have been modified. Try using an unmodified version of LDPS2 |
| LDPS2 shows wrong values. | Calculation updating has been set to manual. Try pressing the F9 key (Recalculate) on your keyboard. If LDPS2 still shows wrong results, check your parameter values. |
| Message "Out of memory". | You need more real memory (RAM) or a larger virtual memory block. See the Windows and Windows 95 manuals. |
| Message "Not enough system resources to display completely" | You need more system resources (memory). See the Windows manuals, or terminate other software running behind LDPS2. When you set zoom control to 100%, sometimes you can avoid the message. |
| Cells show "####" instead of numbers ,or only a part of the text. | Cell content cannot be displayed because the column is too narrow. This is not an error. You just have to change the column's width with the "Format_Column_Width" menu. |
