moss 2007 -- unfair url difference spsite.openweb(...)

this competence seem bit trivial, nonetheless i have means figure out. i am opening adult spsite following perplexing open adult spweb underneath spsite. operative glorious vpc, same site collection/site hierarchy, nonetheless production, i an difference explanation me url unfair i try spsite.openweb(weburl);. i have accurate urls correct.

the code:

  try
        {
            spsite schedulesitecol = new spsite(branchscheduleurl);
            lblerror.text += environment.newline + "site collection url: " + schedulesitecol.url;
            spweb scheduleweb = schedulesitecol.openweb(branchscheduleurl.replace(schedulesitecol.url, "")); //<--- throws blunder line
            splist schedulelist = scheduleweb.getlist(branchscheduleurl + "/lists/" + spcontext.current.list.title);
            relapse schedulelist.getitembyid(int.parse(testid));
        }
        locate (system.exception ex)
        {
            lblerror.text += environment.newline + ex.tostring();
            relapse null;
        }

note:

branchscheduleurl indeed whole url includes url web well.

the cost + exception:

site collection url:

system.argumentexception: unfair url: /internal/scheduletool. during microsoft.sharepoint.spsite.openweb(string strurl, boolean requireexacturl) during microsoft.sharepoint.spsite.openweb(string strurl) during moccbranchschedulelistweb.moccbranchschedulelistv3.getconflictlistitem(string branchscheduleurl, twine testid)system.nullreferenceexception: vigilant anxiety set an instance an object. during moccbranchschedulelistweb.moccbranchschedulelistv3.checkforconflicts(string[] cfcflags1, datetime starttime, datetime endtime, string[] cfcflags2)

note:
spweb i am perplexing open.

am i blank something obvious? any assistance severely appreciated.

thanks.