Hello. I have not used relax in a while and upgraded to the latest 1.3.10 before doing my curve fitting. I am having a problem with the sample script and have pasted a bit out the output below. I am not sure what is going on here. Any help is appreciated. Thanks. Opening the file '500.xpk' for reading. NMRView formatted data file. Number of header lines: 6 Using peak heights. RelaxWarning: Cannot find the spin :@ within the sequence. RelaxWarning: Cannot find the spin :@ within the sequence. RelaxWarning: Cannot find the spin :@ within the sequence. -- Elio Cino