GCTA error: Can not open the file [chr4_PC1.mlma] to write

Hi
I am running GCTA code as below and it seems the mlma model can be run but when it write results to output, it failed. I am very confused because I run the code for each chromosome and all chromosomes work except this one. Is there any suggestion on how to fix it? Thanks a lot in advance!
code: 
for chr in $(seq 4 4); do gcta64 --mlma --bfile chr${chr}_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip --grm ../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet --pheno ../../../previous_genome/geno_data/asmet_gwas_genodata/asmet_pc1pc2pc3.txt --mpheno 1 --qcovar ../../../previous_genome/geno_data/asmet_gwas_genodata/sexage_batch.txt --thread-num 15 --out chr${chr}_PC1& done;


log information: 
*******************************************************************

* Genome-wide Complex Trait Analysis (GCTA)

* version 1.25.2

* (C) 2010-2013 Jian Yang, Hong Lee, Michael Goddard and Peter Visscher

* The University of Queensland

* MIT License

*******************************************************************

Analysis started: Wed Oct 16 23:45:54 2019



Options:

--mlma

--bfile chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip

--grm ../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet

--pheno ../../../previous_genome/geno_data/asmet_gwas_genodata/asmet_pc1pc2pc3.txt

--mpheno 1

--qcovar ../../../previous_genome/geno_data/asmet_gwas_genodata/sexage_batch.txt

--thread-num 15

--out chr4_PC1



Note: the program will be running on 15 threads.



Reading PLINK FAM file from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.fam].

3968 individuals to be included from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.fam].

Reading PLINK BIM file from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.bim].

657004 SNPs to be included from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.bim].

Reading PLINK BED file from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.bed] in SNP-major format ...

Genotype data for 3968 individuals and 657004 SNPs to be included from [chr4_prev_cust_r2gtp3_mafp005_w_asmet_wodupsflip.bed].

Reading phenotypes from [../../../previous_genome/geno_data/asmet_gwas_genodata/asmet_pc1pc2pc3.txt].

There are 3 traits specified in the file [../../../previous_genome/geno_data/asmet_gwas_genodata/asmet_pc1pc2pc3.txt].

The 1th trait is included for analysis.

Non-missing phenotypes of 3968 individuals are included from [../../../previous_genome/geno_data/asmet_gwas_genodata/asmet_pc1pc2pc3.txt].

Reading quantitative covariates from [../../../previous_genome/geno_data/asmet_gwas_genodata/sexage_batch.txt].

3 quantitative covariate(s) of 3968 individuals read from [../../../previous_genome/geno_data/asmet_gwas_genodata/sexage_batch.txt].

Reading IDs of the GRM from [../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet.grm.id].

3968 IDs read from [../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet.grm.id].

Reading the GRM from [../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet.grm.bin].

Pairwise genetic relationships between 3968 individuals are included from [../../../previous_genome/geno_data/asmet_gwas_genodata/samples_w_asmet.grm.bin].

3968 individuals are in common in these files.

3 quantitative variable(s) included as covariate(s).



Performing MLM association analyses (including the candidate SNP) ...



Performing REML analysis ... (Note: may take hours depending on sample size).

3968 observations, 4 fixed effect(s), and 2 variance component(s)(including residual variance).

Calculating prior values of variance components by EM-REML ...

Updated prior values: 1.0252 1.05112

logL: -3378.29

Running AI-REML algorithm ...

Iter. logL V(G) V(e)

1 -3377.32 0.83601 1.20658

2 -3370.02 0.44238 1.54363

3 -3363.86 0.44867 1.54174

4 -3363.82 0.45301 1.54044

5 -3363.81 0.46242 1.53763

6 -3363.80 0.46240 1.53768

7 -3363.80 0.46240 1.53768

Log-likelihood ratio converged.

Calculating allele frequencies ...



Running association tests for 657004 SNPs ...



Saving the results of the mixed linear model association analyses of 657004 SNPs to [chr4_PC1.mlma] ...



Can not open the file [chr4_PC1.mlma] to write.



Analysis finished: Thu Oct 17 01:29:02 2019

Computational time: 1:43:8



thanks,
Lin