PL/SQL :: Getting Error - ORA-06511 - Cursor Already Open?

I have the following code for a Apex(Application Express) project I am developing.

declare
mail_id varchar2(100);
min_skill_cnt number;
skill_cde varchar2(30);
total_leave number;
toal_emp number;

cursor cur is
select S_EMP_EMAIL
from EMP_SKILLS_INFO where SKILLCODE='MGR' and S_EMP_EMAIL = lower(:APP_USER) ;

cursor minskill is
select skill_code,MINRQMT_AM
from skills_code_info
where skill_code in (select skillcode from emp_skills_info where S_EMP_EMAIL = lower(:APP_USER));

cursor leavecnt(v_skill IN VARCHAR2) is
select count(*) from emp_leave_info
where leave_date = :P24_LEAVE_DATE
and emp_email IN (select S_EMP_EMAIL from EMP_SKILLS_INFO where SKILLCODE = v_skill);
cursor empcnt(v_skills IN VARCHAR2) is

[code]...

Ideally this should send email to managers when a particular skill is running short when employee applies for leave. I am getting error that cursor is already open when I run this code. I am not sure which cursor or where it is picking open cursor command.