FCNPC and Run time error 7: "Stack underflow"

[wampiros6]

Hi. I try make script with FCNPC and sometimes i have flood this error

[debug] AMX backtrace:
[debug] Run time error 7: "Stack underflow"
[debug]  Stack pointer (STK) is 0x1051A14, stack top (STP) is 0x1051A08

It appear when i try spawn again npcs.
What means this error and how to solve