Wrong data file name. Check outputs for the data file name and the number of records on the screen. The program does not stop if the wrong file name exists.

Wrong pedigree file name. Check output for the pedigree file name and the number of animals on the screen. The program does not stop if the wrong file name exists.

Wrong positions or formats for observations and effects. Program may not stop and may get wrong results. Check outputs for the number of levels for each effect on the screen.

Missing or skipping one or more fixed lines in the parameter file. Program may stop. Check the missing line.

No extra empty line until OPTION or the end of the parameter file.

Misspelling. Program may stop. Correct the wrong spelling.

Missing an empty last (end) line. Programs may not stop. Parameter, data, and pedigree files may need one more extra line at the end of the file.

(Co)variance matrix is not symmetric, not positive definite, not right sized, … Programs may not stop.

Scale down observations when using Gibbs sampling programs (e.g., 305-day milk yield 10000kg ⇒ 10000/1000 = 10). Program may not stop.

A good result does not mean that your parameter file is correct. Always double-check!