AEGP_GetProjectByIndex() AEGP_ProjectH always NULL

Hi guys, I'm new to After Effects SDK develop. I try to edit project "Panelator" in sdk folder.

In my codes, I want to create an folder in After Effects.

I can get "index = 0" with  `AEGP_GetNumProjects`, but "projH" always be `NULL`

I cannot find any solution now = =

PanelatorUI_Plat::PanelatorUI_Plat(SPBasicSuite* spbP, AEGP_PanelH panelH,
	AEGP_PlatformViewRef platformWindowRef,
	AEGP_PanelFunctions1* outFunctionTable)
	: PanelatorUI(spbP, panelH, platformWindowRef, outFunctionTable),
	i_prevWindowProc(NULL)
{
	S_sp_basic_suiteP = spbP;
        …… OTHER CODE ……
}


void PanelatorUI_Plat::CreateNormalFolder() {
	A_Err	err		= A_Err_NONE;
	AEGP_ProjectH	projH	= NULL;
	A_long		index	= -100;

	AEGP_SuiteHandler	suites(S_sp_basic_suiteP);
	ERR(suites.ProjSuite5()->AEGP_GetNumProjects(&index));
	ERR(suites.ProjSuite5()->AEGP_GetProjectByIndex(0, &projH));  // &projH returns NULL...
	
	A_UTF16Char folder_name[256] = {'a', 'b'};
	ERR(suites.ItemSuite9()->AEGP_CreateNewFolder(folder_name, NULL, NULL));
}

Thanks for any discussion.