Error message

[JB999]

I just started receiveing the following error message in Surveyor and it now pops up every one in a while. I click on 'continue' and all appears OK:
-----------------------------------------------------------
Thread Exception ER NullReference, line 1326, file

Stack dump

Function $Permit{} Train:: TakePermitOnTrack (bool), line-1
Function $avoid$ Train::Init(), line 1397
------------------------------------------------------------

I would appreciate it if someone could tell me what this means.
Thanks in advance.

 

[nismit]

Ode to a missing object

Posting Deleted.

 

[JB999]

Thanks, nismit

Thanks for tyhe reply... I'll look for the problem