Prog works w/ONLINE, core dumps w/SE...?

I have strange problem that occurs on the Informix standard engine only. Actually, I wrote the Informix-4gl program and compiled it under the Online engine. It was tested successfully and the executable was sent out to the sites where they have standard engines. When I run this report program after selecting about 200 records, I got this error message from the standard engine sites (on Online, it did not fail.): Program stopped at "-----.4gl", line number 345. SQL statement error -565. Cannot read sorted rows. System error number -101. ISAM error: file is not open. I ran this program with about ten records and it works. I tried to see where the error has occurred and could not see anything wrong. Someone suggested I compile this program on standard engine and I did. Then the report went to a Memory fault -- core dumped just in the middle of the report. I debugged to see where it got the core dumped and found it stopped at the string concatenation (i.e. let strng = strng[1,i-1], "x", strng[i+1,len]). I wrote a C function to concatenate that string above and it went through this C function but got core dumped on the next string concatenation, and then the next string concatenation, etc. I tried to "re-write" the whole program by using more functions and procedures and compiled on the Standard engine but still got either "Bus error -- core dumped" or "Memory fault -- core dumped" messages. Could you explain this ?? Online 4GL: Version 4.00.UH2 SE 4GL: Version 4.00.UD3 -- No tagline'ing at work permitted.