Help me!!!!!! C-ISAM file open

Hello! I programmed using C-ISAM library at Network Environment. I make one program, and I used this program at Netware + DOS, and work fine. I wish to use this program at Windows NT + DOS, but I receive "File Access violation" error. I used FLAG utility in Netware, but not exist FLAG util in Windows NT. I asked to Microsoft, they said "Use file sharing open mode". I think this problem is file open method, too. I opend in program by automatic option. I want to know how to file sharing mode open in C-ISAM library. Or, Where I ask this problem. Please help me.