Call Function 'ENQUE_READ' - Lock doesn't refresh

Hello Folks,

I have written 'Call Function 'ENQUE_READ' before updating MR21 using BDC - Call Transaction.

The above code is written in a Z Call Function 'Starting New Task'.

The problem i am facing is with the 'Call Function 'ENQUE_READ'.

Once I have entered a lock (MM02 in change mode) on MARC table FM 'ENQUE_READ' returns a number '1'.

Which means 1 user has locked MARC.

However when i come out of the lock (MM02 is closed) and try to update MR21 again, FM 'ENQUE_READ' it still returns '1',

Need to know why MR21 is getting locked permanently for a material even after I come out of lock i.e. (MM02 is closed).

This is not allowing me to update MR21.

This is an urgent issue.. will reward more points for answers.

Thanks !!