error with bedtools slop

Hi, 

I am trying to run a bedtools slop on my.bed file and hg19.genome

bedtools slop -i H3K27me3.bed -g hg19.genome -b 30

I get the following error:

Less than the req'd two fields were encountered in the genome file (genomes/hg19.genome) at line 2.  Exiting.

Any suggestions?

Thanks in advance

Samad