Cause : Block no. of block search forward is no UP call comes when the block number for the main program (level 0), which was transferred with block search, does not contain a subprogram call for subprogram level 1.

• For the block search function, a block number with a subprogram call must be specified as the block number for the main program (level 0) if a block search is to be performed in subprogram level 1.