I've got a problem with a legacy system written in Fox 2.6 for DOS

Got a table called assessmt.
Program crashes when a locate for command is issued.

Code is as follows:

Select assessmt
Set order to 2
locate for cl_ref=g_cl_ref and !EMPTY(as_pctype)

Using the command window. If I use assessmt and issue the locate for command, everything is fine. If I use assessmt, set the order to 2, and then issue the locate for command I get a record out of range error.

Can anyone tell me why this is please?

Phil