Possible reasons for SAPLSENT (ENQUEUE_READ) time out

One of our most frequent time out runtime errors found in ST22 is in program SAPLSENT (ENQUEUE_READ).

The line it always times out on is line 191, "CLEAR ENQ."

REFRESH ENQ.

LOOP AT raw_enq.

>>> CLEAR ENQ.

MOVE-CORRESPONDING RAW_ENQ TO ENQ.

Other information provided.

Program............. "SAPLSENT"

Screen.............. "SAPMSSY1 3004"

Screen Line......... 2

Transaction......... " "

Call Program........."SAPLERFC"

Function Module..... "ARFC_DEST_SHIP"

Call Destination.... "NONE"

Any ideas that could help me address this situation? Let me know if I can post more info that would help troubleshoot.

I appreciate it!