Hi LizMB,
Without evaluating your model in detail, that error is due to a transfer not being completed (transfer request while entity is still being transferred previously). It is typically when you make use of a transfer step and either not end the transfer (using and "End Transfer" step), before transferring it again or when Simio attempts to transfer the entity (due to inherent worker/node/vehicle logic) before the end transfer is completed. It could also be if you interrupt something before a transfer action has completed. What also happens is when you have processes executing e.g. On-Entered and the same entity executes one or more such processes at the same time, resulting in a inherent transfer request before the previous has completed.
It could be a matter of timing or the sequence of events, or a problem in your logic. When you are using a transfer step in your logic it is useful to have a process with an End Transfer step that is either subscribed to certain events or executed on an event triggered e.g. StationName.Entered. If you were to interrupt a process/action, you can either fire the trigger event or just use logic to test whether the entity has transferred. With an add-on process it is best to understand the sequence of events happening in the Simio logic and ensure certain logic gets completed first or that you don't have parallel requests at the same time.
As you can see there are multiple ways to address something like this and your approach depends on your logic and the system being modeled.
Good Luck.
H
