"Shader has errors or is not supported by your graphics card."

I have the following shader, which shows the above line when I look at it in the inspector. It does not generate any errors/warnings if I right click the asset and do a reimport, though.

 Shader "Architect/Bezier Line" 
 {
     // Bound with the inspector.
      Properties 
      {
         _Color ("Main Color", Color) = (1.0, 1.0, 1.0,1.0)
            _Start ("Start", Vector) = (0.0, 0.0, 0.0)
            _End ("End", Vector) = (0.0, 0.0, 0.0)
     }
 
     SubShader 
     {
         Pass 
         {
             Blend SrcAlpha one
 
             CGPROGRAM
             #pragma target 5.0
             
             #pragma vertex vert
             #pragma fragment frag
             
             #include "UnityCG.cginc"
             
             // The same point data structure used by both the compute shader and the shader.
 //            struct Point
 //            {
 //                float t;
 //            };
             
             // structure linking the data between the vertex and the fragment shader
             struct FragInput
             {
                 float4 color : COLOR;
                 float4 position : SV_POSITION;
             };
             
             // The buffer holding the points shared with the compute shader.
             StructuredBuffer<float> pointBuffer;
             
             // variables from the properties.
             float4 _Color;
             float3 _Start;
             float3 _End;
             
             FragInput vert (uint id : SV_VertexID, uint inst : SV_InstanceID)
             {
                 FragInput fragInput;
                 
                 // apply color
                 fragInput.color = _Color;
                 
                 // position computation
                 float t = pointBuffer[inst];
 //                
                 float3 p0 = _Start;
                 float3 p3 = _End;
 //                
                 float dist = distance(p0, p3);
 //                
                 float3 p1 = float3(p0.x + clamp(dist, 0.0, 400), p0.y, 0);
                 float3 p2 = float3(p3.x - min(dist,200), p3.y, 0);        
                 
                 float3 final = (pow(1.0-t,3.0) * p0) + (3.0 * pow(1.0-t,2.0) * t * p1) + (3.0 * (1.0-t) * pow(t,2.0) * p2) + (pow(t,3.0) * p3);
                 
                 fragInput.position = mul (UNITY_MATRIX_MVP, float4(final, 1));
                 
                 return fragInput;
             }
             
             // this just passes through the color from the properties
             float4 frag (FragInput fragInput) : COLOR
             {
                 return fragInput.color;
             }
             
             ENDCG
         
         }
     }
 
     Fallback Off
 }

Can anyone help me out here?