Please ensure that the parameters KY KZ are specified before the CHECK CODE command. If these are and you are still getting the failure, ask for a TRACK 2 output for the design and look at the actual slenderness calculated and how that compares with the allowable value. Also please note that TMAIN sets the upper limit of slenderness for members subjected to tension. For members subjected to compression, the limit is set using the MAIN parameter.
If you have additional queries, please upload the model and mention the member number in question.
If you have additional queries, please upload the model and mention the member number in question.