GSL ERROR: matrix is singular in lu.c at line 449 errno 1

[huma-cloud]

I’m getting this error while running GEMMA Linear Mixed Model (LMM) association analysis.
$gemma -bfile $plink_file -p $phenotype_file -k $kinship_file -lmm 1 -c $covariate_file -o $output_name

I changed the covariate table from PC1, PC2, PC3, phenotype1, phenotype2, phenotype3 to Breed, PC1, PC2, PC3, phenotype1, phenotype2, phenotype3. After changing the covariate table, I got this error. I just want to add a fixed effect.
what is the solution of this error?