# CMAQ-DDM Error: number of in Jacobian does not match N\_GC\_SPC **URL:** \ **Category:** CMAQ-DDM-3D\ **Created:** [June 3, 2019, 2:21am UTC](https://forum.cmascenter.org/t/cmaq-ddm-error-number-of-in-jacobian-does-not-match-n-gc-spc/730 "2019-06-03T02:21:22Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![maplewind](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@maplewind](https://forum.cmascenter.org/u/maplewind)\ **Post date:** [June 3, 2019, 2:21am UTC](https://forum.cmascenter.org/t/cmaq-ddm-error-number-of-in-jacobian-does-not-match-n-gc-spc/730/1 "2019-06-03T02:21:22Z")
hello，when I was running CMAQ-DDM-3D(v5.2),there is the following error:Number of species in Jacobian does not match N\_GC\_SPC. I have tried to compile DDM with two mechnisms (cb05\_tucl and cb05\_e51),the error is the same . Would you please help me with the problem? Thanks a lot! ---
**Author:** ![sergey](https://avatars.discourse-cdn.com/v4/letter/s/9fc348/32.png) [@sergey](https://forum.cmascenter.org/u/sergey)\ **Post date:** [June 20, 2019, 6:10pm UTC](https://forum.cmascenter.org/t/cmaq-ddm-error-number-of-in-jacobian-does-not-match-n-gc-spc/730/2 "2019-06-20T18:10:30Z")
Hello and sorry for the late response. It is possible that these mechanisms have been modified after the implementation of DDM into the model. Which specific mechanism do you want to use? I can try to compile it here and let you know if any updates are necessary. Sergey ---
**Author:** ![maplewind](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@maplewind](https://forum.cmascenter.org/u/maplewind)\ **Post date:** [June 21, 2019, 7:29am UTC](https://forum.cmascenter.org/t/cmaq-ddm-error-number-of-in-jacobian-does-not-match-n-gc-spc/730/3 "2019-06-21T07:29:32Z")
Thanks for your reply！The mechanism I used is cb05\_tucl.The updates you mentioned means that I have to recompile it later with modifying source code?