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TLIB 5.51a gives a more informative error message. You'll have to help us out by providing us with a few sample project files, and by testing it for us. The bug is fixed in 5.04f. The library is actually undamaged and works fine with TLIB 5.04f or later. When working in DOS, we had a DOS environment variable referenced in the TLIB.CFG file, to set the named project level.