Dear all, I have problem during my denovo assembly process,

I have launched velveth for mypaired.fastq containing 600 millions reads in total (length 150) :

velveth out_21 21 -fastq -shortpaired mypaired.fastq

for this steps all were ok

then I launched velvetg on out_21/:

velvetg out_21 -scaffolding no -min_contig_lgth 2000

unfortunately I had this error :

[0.000000] Reading roadmap file out_21/Roadmaps velvetg: Can't calloc 18446744071893837925 Annotations totalling 18446744044658132560 bytes: Cannot allocate memory

have you any ideas about this error? how can i fix it ? thank you in advance .