help with SQL procedure conversion

Hi Guys, I need some in SQL conversion from Oracle to SQL Server...Here is the procedure in T-SQL..When I run the below SQL in SQL Server, it is going in infinite loop. When I click stop, I am getting the error ......
"Invalid length parameter passed to the substring function."
at the following line
SELECT @.RoleID_in = CONVERT(NUMERIC(8, 2), SUBSTRING(@.UserRoles_in, 1, CHARINDEX(',', @.UserRoles_in) - 1))
----
DECLARE @.objid_in INT
DECLARE @.objclass_in INT
DECLARE @.userid_in INT
DECLARE @.userRoles_in VARCHAR(3000)
DECLARE @.RoleID_in INT
DECLARE @.cnt INT

DECLARE csr CURSOR FOR
SELECT * FROM objectACL
OPEN csr
WHILE (0 = 0)
BEGIN --(

fetch NEXT FROM csr INTO @.objid_in, @.objclass_in, @.userid_in, @.userRoles_in
IF (@.@.FETCH_STATUS = -1)
BREAK
SELECT @.UserRoles_in = SUBSTRING(@.UserRoles_in, 2, LEN(@.UserRoles_in))
WHILE (0 = 0)
BEGIN --(
SELECT @.RoleID_in = CONVERT(NUMERIC(8, 2), SUBSTRING(@.UserRoles_in, 1, CHARINDEX(',', @.UserRoles_in) - 1))
SELECT @.cnt = COUNT(*) FROM nodetable WHERE objtype = 21 AND id = @.RoleId_in
IF ( @.cnt = 0 )
BEGIN
INSERT INTO error_report VALUES( 'ObjectACL' , '0' , 'UserRoles refering to Non-existing Role : ' + CAST(@.RoleID_in AS VARCHAR) )
END
SELECT @.UserRoles_in = SUBSTRING(@.UserRoles_in, LEN(@.RoleID_in) + 2, LEN(@.UserRoles_in))
IF ( @.UserRoles_in is null )
BEGIN
BREAK
END
END --)
END --)
close csr
DEALLOCATE csr
GO
------

Corresponding procedure in Oracle
-----
declare
cursor csr is select * from objectACL;

objid_in number;
objclass_in number;
userid_in number;
userRoles_in varchar2(3000);
RoleID_in number;
cnt number;

begin
open csr;
loop
fetch csr into objid_in, objclass_in, userid_in, userRoles_in;
exit when csr%notfound;

UserRoles_in := substr(UserRoles_in, 2);

loop
RoleID_in := to_number(substr(UserRoles_in, 1, instr(UserRoles_in, ',')-1));
select count(1) into cnt from nodetable where objtype=21 and id=RoleId_in;
if (cnt =0) then
insert into error_report values ('ObjectACL', '0', 'UserRoles refering to Non-existing Role : '||RoleId_in);
end if;

UserRoles_in := substr(userRoles_in, length(RoleId_in)+2);

if (userRoles_in is null) then
exit;
end if;
end loop;
end loop;
close csr;
end;
/
------Dear Lord, PSQL is a sucky language. That is pretty near unreadable.

Do yourself a favor and don't even try to convert this into TSQL directly. Oracle developers love cursors, but set-based operations are almost always easier to debug and run faster. I'd better dollars to doughnut holes you don't even need a cursor for this.

Post your table layout and a description of what you are trying to do.