This may be caused by a corrupt MSK file, or by misaligned coverages. MAPJOIN searches for matching nodes within a fuzzy tolerance, and if there are ambiguous cases, the (NODPOL) error occurs.
1. Deleting the MSK files and/or rebuilding topology for the original coverages usually solves the problem. Note that a new MSK file is created during the MAPJOIN process to enable partial processing of the border areas of the maps. The new MSK file is not related to pre-existing MSK files in the input coverages.
Note: The MSK file is a bitmap file containing the map extent of a previous editing session in ARCEDIT. It is used by BUILD and CLEAN to process only those portions of the coverage that were last updated. The MSK file is deleted after the coverage topology has been updated.
2. The coverages should be edgematched. Choose the more spatially accurate coverage as the LINK coverage and edgematch the less accurate coverage to it.
If the coverages have already been edgematched, specify a larger fuzzy tolerance for both coverages using the TOLERANCE command. Alternately, CLEAN each coverage separately with appropriate fuzzy tolerance values and then use MAPJOIN. Finding the appropriate fuzzy tolerance value requires an understanding of the minimum coordinate resolution for the coverages. As a rule of thumb, increase the fuzzy tolerance by increments of 1 1/2 or decrease it by 1/4 until the error message no longer occurs.
Sometimes the problem can be resolved by joining the coverages in parts. For example, if you have 12 coverages to join, you might first try joining 6 coverages together. If the MAPJOIN still fails, try joining only 2 coverages together. This approach allows you to single out one or two problem coverages which are causing the entire process to fail. Once you have fixed the problem coverages, you should be able to join them to the rest of the coverages.