Hello,
If not already solved, in your SOURCES FILE, the final time may be 150. If you simulation should last more than 150 s, final time in the SOURCES FILE should be at least a little bit more than the duration otherwise you may get this error message (due to roundings).
You can add an additional line with the same values as the ones for time 150 and time bigger, e.g. 1000.
Hope this helps,
Chi-Tuan