According to documentation https://admhelp.microfocus.com/sv/en/5.1/Help/Content/UG/t_fixed_length.htm

The actual Message Length value in the incoming message must be the size of the whole message—it must include the number of bytes indicating its length, type, and all fields. For example, suppose your payload is ABCDEFG_123456, the message type is one byte with the value ‘T’, and the message length is denoted in the first two bytes using a numeric data type. The whole message would be 16TABCDEFG_12345 with a length of 16.
Note: If the length always deviates by a constant value, indicate this in the Data column (described above).

If this doesn't help can you share your service description files and sample message?

Hi Jakub

I understand what you refer to in manual but have to tell you that this client real-service message is not standard. Let say if payload = aaa... (108bytes), type = bbb... (20bytes), length = 128, the whole message length will be 130 because it include first 2bytes (the length).

we using wireshark to check unsuccess message, it is show 128length (fail.jpg). However I use LoadRunner to push stream with 128length (I cut off last 2 spaces) result is similar to SV (real service not accept it), but when I produce stream with 130length (success.jpg) it is success.

I think, everything should be solved if SV not automatic cut the whole message to be as defined in length. Is there anyway to disable this option or any other ways please...

By the way, I couldn't send attached files in this post. I will send to you via e-mail.

Received resources in the email. Solution is to add offset 2 bytes to the length specified in the message header. This can be done by specifying the offset in the Data column. For more info, please see help referenced above.