this is because the format of the first line in the simulation output.
the number of replicates should be in the third column separated by " ".
For example:
"ms 10 100 ......"
100 is the number of replicates. Sometimes we you do simulation using msms, the third column may not be the number of the replicates, and thus leads to error.
To solve the problem, you can modify the first line manually, making sure the third column is the number of replicates.
you can also do this by using bash sed command!
the output as you described seems different from the expected: