Hello again,
I did some changes,
and marked the custom-fields for the post-type, which I use, to be active.
And I had other post meta keys, which was not created by types.
I used the same code as above, and only changed the meta key, and the value was saved properly in the database.
so it seems that the types plugin is having problem when I am using
update_post_meta
to save the new value.
please help me, I need assistance.
regards