How to use AlphaTest with a CGPROGRAM

I've used AlphaTest Greater 0 as an 'Alpha Cutoff' type of effect for a shader I'm using (Because I need ZWrite On), however when I try to implement a CGPROGRAM to add a Tint over my texture, it seems to be overriding the AlphaTest.

The result looks like so:

But I want it to look like this:

I've just used the Sprite-Default.shader from unity to add the Color tint. I'm obviously a rookie with this, and I'd like to understand whats going on. Any help would be great!

And here is my Shader as it currently stands:

 Shader "Unlit/planetDefault"  {
          Properties 
          {
              _MainTex ("Base", 2D) = "white" {}
              _Color ("Tint", Color) = (1,1,1,1)
          }
      
          SubShader 
          {
             
              Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Opaque"}
              LOD 200
 
              Cull Off
              ZWrite On
              Blend SrcAlpha OneMinusSrcAlpha 
              AlphaTest Greater 0
 
              Pass 
              {
 
         CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma multi_compile _ PIXELSNAP_ON
             #include "UnityCG.cginc"
             
             struct appdata_t
             {
                 float4 vertex   : POSITION;
                 float4 color    : COLOR;
                 float2 texcoord : TEXCOORD0;
             };
 
             struct v2f
             {
                 float4 vertex   : SV_POSITION;
                 fixed4 color    : COLOR;
                 float2 texcoord  : TEXCOORD0;
             };
             
             fixed4 _Color;
 
             v2f vert(appdata_t IN)
             {
                 v2f OUT;
                 OUT.vertex = UnityObjectToClipPos(IN.vertex);
                 OUT.texcoord = IN.texcoord;
                 OUT.color = IN.color * _Color;
                 #ifdef PIXELSNAP_ON
                 OUT.vertex = UnityPixelSnap (OUT.vertex);
                 #endif
 
                 return OUT;
             }
 
             sampler2D _MainTex;
             sampler2D _AlphaTex;
             float _AlphaSplitEnabled;
 
             fixed4 SampleSpriteTexture (float2 uv)
             {
                 fixed4 color = tex2D (_MainTex, uv);
 
 #if UNITY_TEXTURE_ALPHASPLIT_ALLOWED
                 if (_AlphaSplitEnabled)
                     color.a = tex2D (_AlphaTex, uv).r;
 #endif //UNITY_TEXTURE_ALPHASPLIT_ALLOWED
 
                 return color;
             }
 
             fixed4 frag(v2f IN) : SV_Target
             {
                 fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
                 c.rgb *= c.a;
                 return c;
             }
         ENDCG
 
              Lighting Off
              SetTexture [_MainTex] 
              {
                 Combine texture
              } 
              }
 
          }
      }