Error locating program: prep_reads when testing installation of tophat

[Wed Oct  5 20:55:25 2011] Preparing output location ./tophat_out/
[Wed Oct  5 20:55:25 2011] Checking for Bowtie index files
[Wed Oct  5 20:55:25 2011] Checking for reference FASTA file
[Wed Oct  5 20:55:25 2011] Checking for Bowtie
    Bowtie version:             0.12.5.0
[Wed Oct  5 20:55:25 2011] Checking for Samtools
    Samtools Version: 0.1.17
[Wed Oct  5 20:55:25 2011] Checking reads
    min read length: 75bp, max read length: 75bp
    format:         fastq
    quality scale:     phred33 (default)
Error locating program:  prep_reads



I solved this problem simply by using the /path/to/install/bin/ as the current directory and putting all the excutables into this directory and run the data on this very directory!!! sounds stupid but it worked!!!