[galaxy-dev] GATK fasta file not found ERROR

Dear Developers, I am using GATK for first time. I am doing Targeted reseq Analysis. while i am running Unified Genotyper in Galaxy interface. it gives error message as mentioned below.. "ERROR MESSAGE: The fasta file you specified (/tmp/tmp-gatk-WBrGTf) does not exist." But i places the Fasta file path in .loc file. Also could anyone tell what are the preprocessing steps before using Bam file for Unified Genotyper?? Your answers are very much Appericiated. Thanks Sridhar