Message: No explicit calls of '<FB name>' allowed. <value of attribute 'no_explicit_call'>

Possible error cause: A function block with the no_explicit_call attribute has been called.

{attribute 'no_explicit_call' := 'Call of this FB is not allowed'}
FUNCTION_BLOCK FB1
VAR_INPUT
END_VAR
VAR_OUTPUT
END_VAR
VAR
END_VAR

PROGRAM PLC_PRG
VAR
    myFB: FB1;
END_VAR

myFB();

Message:

C0554: No explicit calls of 'FB1' allowed. Call of this FB is not allowed.

Error correction: Delete the attribute pragma.