can't open gnucash file

[suk wah bernstein]

last month i used gnucash the first time. imported quicken files as qif.
entered data. reconciled. now i go in for current month's work. in 'open'
box, there is

personal accounts qif 798.6 kb modified 9/22/2011'

click 'open' following pops up.

No suitable backend was found for
file://Users/SukWahB/Documentss/sukwah/PersonalFinan.gnu/PersonalAccounts.qif

also tried to go to drop down menu of File and click on
Joint Personal Checking Gnucash.gnucash

following pops up.

The file file://Users/SukWahB/Documents/sukwah/PersonalFinan.gnu/Joint
Personal Checking.GnuCash.gnucash could not be found.

pls advise.

respect
suk wah bersntein