GROMACS version: 2022.4 Hi, I am working with a GPCR system embedded in lipid bilayer and water. I want to select every water (group 31 in index file) that is situated below 4A from a particular residue of the protein (group 43), so the command has been used as I have seen being used in earlier queries: gmx select -f input.xtc -s input.tpr -n input.ndx -select ‘group 31 and within 0.4 of group 43’ -on output.ndx

But I get multiple syntax errors: Error in user input: Invalid command-line options In command-line option -select Invalid selection ‘and’ Near ‘and’ syntax error In command-line option -select Invalid selection ‘within’ While parsing ‘within’ ‘within’ should be followed by a value/expression ‘of’ is missing In command-line option -select Invalid selection ‘0.4’ Near ‘0.4’ syntax error In command-line option -select Invalid selection ‘group’ Near ‘group’ syntax error In command-line option -select Near ‘�’ syntax error Where am I going wrong? I have tried few other combinations too, but those were also followed up similar syntax errors? Thanks in advance