A little confuse

[infotechsys at pivot.net]

When I run this code in the pdb it works.
 accountNbr = 1
 for testLine in ftest.readlines():
        acct = testLine[1:2]             #there account number
        if accountNbr == int(acct):
            accountNbr = accountNbr + 1

When I run without the debugger I get this error.

 File "./casco.py", line 62, in process
    if accountNbr == int(acct):
ValueError: invalid literal for int(): "

Can someone explain?