Graphic3d_ShaderProgram PushVariableFloat Update crash

Hello everyone, when I used Graphic3d_ShaderProgram of occt 7.4.0, I wrote XRay.vs and XRay.fs two coloring fragments. Add the shader to the selected model through the first code below, but in myAISContext-> CurrentViewer ()-> Update (); when the program crashes, but if you remove the three PushVariableFloat places and change the uniform in XRay.fs to a local variable, the program can execute normally and the shader can also function normally. I wonder if you have encountered this problem? Thank you.

Handle(Graphic3d_ShaderProgram) aProgram;
aProgram = new Graphic3d_ShaderProgram();
Handle(Graphic3d_ShaderObject) vertexshader=Graphic3d_ShaderObject::CreateFromFile(Graphic3d_TOS_VERTEX, maSrcVert);
Handle(Graphic3d_ShaderObject) fragmentshader = Graphic3d_ShaderObject::CreateFromFile(Graphic3d_TOS_FRAGMENT, maSrcFrag);
if (vertexshader.IsNull())
{
	return;
}
if (fragmentshader.IsNull())
{
	return;
}
if (!vertexshader->IsDone())
{
	return;
}
if (!fragmentshader->IsDone())
{
	return;
}
Standard_Boolean attach1=aProgram->AttachShader(vertexshader);
Standard_Boolean attach2=aProgram->AttachShader(fragmentshader);
if ((!attach1)||(!attach2))
{
	return;
}
if (!aProgram->IsDone())
{
	return;
}
Standard_Boolean set1=aProgram->PushVariableFloat("edgefalloff", 2.0f);
Standard_Boolean set2=aProgram->PushVariableFloat("intensity", 2.0f);
Standard_Boolean set3 = aProgram->PushVariableFloat("ambient", 0.01f);
if ((!set1)||(!set2)||(!set3))
{
	return;
}
Handle(Prs3d_ShadingAspect) aNewAspect = new Prs3d_ShadingAspect();
aNewAspect->Aspect()->SetShaderProgram(aProgram);
//aNewAspect->Aspect()->SetAlphaMode(Graphic3d_AlphaMode::Graphic3d_AlphaMode_Blend);
selobject->Attributes()->SetShadingAspect(aNewAspect);

myAISContext->CurrentViewer()->Update();

// XRay.vs
varying vec3 N;
varying vec3 I;
varying vec4 Cs;

//! Computes the normal in view space
vec3 TransformNormal (in vec3 theNormal)
{
  vec4 aResult = occWorldViewMatrixInverseTranspose
               * occModelWorldMatrixInverseTranspose
               * vec4 (theNormal, 0.0);
  return normalize (aResult.xyz);
}

//! Entry point to the Vertex Shader
void main ()
{
  N = TransformNormal (occNormal);
  vec4 P = occWorldViewMatrix * occModelWorldMatrix * occVertex;
  I = P.xyz-vec3 (0);
  Cs = occColor;
  gl_Position = occProjectionMatrix * occWorldViewMatrix * occModelWorldMatrix * occVertex;
}

// Xray.fs
// vertex to fragment shader io
varying vec3 N;
varying vec3 I;
varying vec4 Cs;

// globals
uniform float edgefalloff;
uniform float intensity;
uniform float ambient;

// entry point
void main ()
{
    float opac = dot (normalize (-N), normalize (-I));
    opac = abs (opac);
    opac = ambient + intensity * (1.0-pow (opac, edgefalloff));
    // opac = 1.0-opac;

    gl_FragColor = opac * Cs;
    gl_FragColor.a = opac;
}