[gmx-users] Error select a group gmx_density

[Poncho Arvayo Zatarain]

Hello Gromacs users: I´m trying to obtain the density og a mixed membrane plus a protein. I use the command line:  gmx_gpu density -ng 4 -f npt.xtc -s npt.tpr -o density.xvg. And this appears:
Reading file npt.tpr, VERSION 5.0.4 (single precision)

Select 4 groups to calculate density for:
Group     0 (         System) has 58780 elements
Group     1 (          Other) has 58780 elements
Group     2 (            PROTEIN) has   576 elements
Group     3 (           DPPC) has 16640 elements
Group     4 (           DPPE) has 15488 elements
Group     5 (           TIP3) has 26076 elements
Select a group: 3 & 4 & 2 & 5
Selected 3: 'DPPC'
Select a group: Error: No such group '&'
Select a group: Selected 4: 'DPPE'
Select a group: Error: No such group '&'
Select a group: Selected 2: 'PROTEIN'
Select a group: Error: No such group '&'
Select a group: Selected 5: 'TIP3'
Last frame       5000 time 210000.000

Read 5001 frames from trajectory. Calculating density

Is there anything wrong with the command line or with Select a group: Error: No such group '&'? Also i tried with 3 | 4 | | 2 | 5 and appears the same error but with | instead &? What about the Last frame 5000 time 210000.000? Why 5000 and not 210000.000?. Also, and .xvg file is generated
Thanks