UDT, is it downloadable to PLC?

hello guys, in my company i was trying to add some new fuctionallity to my machine. and so i've added some new DBs, FCs, FBs & 1 UDT (my first time to use a UDT).
i downloaded all of them to the PLC, but i couldn't download the UDT. so i guessed it is undownloadable to the PLC.

the problem is after i downloaded the new DBs, FCs, FBs and called them the PLC went out of RUN mode and made an error.
so my question is: does that have anything to do with UDT defination? & how do i download it to the PLC if needed?

A UDT cannot be downloaded to the plc. Use the diagnostics buffer and or stacks to determine the cause of the error.

Thank u very much, i'll try that...