error when coping a block from a custom block library

im using s-functions to build a custom target block library for pic microcontrollers, i built the library and save it (the block) as one (not a model with a bunch of blocks), but when i try to copy any block from the library i have create to a actually model i get an error (shown in the image below)

i didnt find anything related to this on matlab help.

does anyone know what this error is and how to fix it?

thanks, isaac.

this one can be better visualized