# Problem with residuetypes.dat

**URL:** <https://gromacs.bioexcel.eu/t/problem-with-residuetypes-dat/1130>\
**Category:** User discussions\
**Created:** [November 20, 2020, 4:13pm UTC](https://gromacs.bioexcel.eu/t/problem-with-residuetypes-dat/1130 "2020-11-20T16:13:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tiacava95](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@tiacava95](https://gromacs.bioexcel.eu/u/tiacava95)\
**Post date:** [November 20, 2020, 4:13pm UTC](https://gromacs.bioexcel.eu/t/problem-with-residuetypes-dat/1130/1 "2020-11-20T16:13:14Z")

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GROMACS version: 2020.3  
GROMACS modification: Yes

Good morning everyone.  
I added a new residue to the amber99SB.ff force field following the guide present in the gromacs manual. When I use pdb2gmx it shows a fatal error saying that the novel residue has type “Other” although I added it to the residuetypes.dat file as type “Protein”. How can I solve this?

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**Author:** ![alevilla](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/alevilla/32/439_2.png) [@alevilla](https://gromacs.bioexcel.eu/u/alevilla)\
**Post date:** [November 23, 2020, 10:08am UTC](https://gromacs.bioexcel.eu/t/problem-with-residuetypes-dat/1130/2 "2020-11-23T10:08:32Z")

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Hi,  
you can check that

- pdb2gmx is reading the correct residuetypes.dat
- the sintax of residuestypes.dat is correct
- the new residue is well defined in all the aminoacid.\* file of the modified amber force fields  
Best regards  
Alessandra