error information in PCA

[Y Z]

Hello, everyone,

I just met the following error in the compiled plumed:

void PLMD::PlumedMain::readInputWords(const std::vector<std::__cxx11::basic_string<char> >&)

PLUMED: ERROR

PLUMED: I cannot understand line: PCA LABEL=pca USE_OUTPUT_DATA_FROM=cc METRIC=OPTIMAL NLOW_DIM=2

PLUMED: Maybe a missing space or a typo?

However, in my another computer, the script run successfully and does not given me the above error message. Both the plumed in two computers are 2.9 version and I have checked that the dimered module are compiled. 

Does anyone know what happened?

Thank you so much.

YW ZHANG