fixed error message, docu.
fixed error message, docu.

at7/ensembl,willmclaren/ensembl,willmclaren/ensembl,Ensembl/ensembl,Ensembl/ensembl,muffato/ensembl,danstaines/ensembl,muffato/ensembl,danstaines/ensembl,at7/ensembl,at7/ensembl,mjg17/ensembl,james-monkeyshines/ensembl,muffato/ensembl,james-monkeyshines/ensembl,muffato/ensembl,mjg17/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,mjg17/ensembl,mjg17/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,danstaines/ensembl,at7/ensembl