SWI in ARTX

Hello,
i' am working with ARTX Arm and have the following problem. When SWI Function calls another SWI Function, after return it remains in Supervisor Mode. Is it not allowed to call a SWI function from another SWI function?

void TestSwi2(void) __swi(18)
{
static int cnt=0x5555;
	cnt++;
}

void TestSwi1(void) __swi(19)
{
	TestSwi2();
}

void main (void)
{
   TestSwi1();
}