QuickSearch:   
by PDB,NDB,UniProt,PROSITE Code or Search Term(s)  
Sorry,
   '5TEI' is not recognized as a valid PDB/NDB code.

Please check the spelling.

It might also be an obsolete entry or the entry might not be released yet.
Check '5TEI' directly at the RCSB Protein Data Bank.

Or maybe you wanted to do a QuickSearch with '5TEI' as search term and not as PDB/NDB code.