Why would using a Stencil stop my scrolling effect from working?

Hi,

I'm trying to do a pulse effect for some UI. I've had an effect working but then tried to adapt it so it'll work with a mask. However, when adding the stencil operations required, the effect stops. Can somebody explain why? The shader is below. I'm scrolling the UV's on line tex through a script on the other end and the uv's definitely still scroll.

Code (CSharp):

1. Shader "Unlit/GraphLinePulse"
2. {
3.     Properties
4.     {
5.         [PerRendererData]
6.         _MainTex ("Texture", 2D) = "white" {}
7.         _LineTex("LineTex", 2D) = "white" {}
8.         _Color("Tint", Color) = (1,1,1,1)
9.         _FullLineColor("FullLineCol", Color) = (1,1,1,1)
10.  
11.         _StencilComp("Stencil Comparison", Float) = 8
12.         _Stencil("Stencil ID", Float) = 0
13.         _StencilOp("Stencil Operation", Float) = 0
14.         _StencilWriteMask("Stencil Write Mask", Float) = 255
15.         _StencilReadMask("Stencil Read Mask", Float) = 255
16.  
17.         _ColorMask("Color Mask", Float) = 15
18.         //_Color("Default", Color) = (0,0,0,1)
19.     }
20.     SubShader
21.     {
22.         Tags{ "Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent" }
23.  
24.         Stencil
25.         {
26.             Ref[_Stencil]
27.             Comp[_StencilComp]
28.             Pass[_StencilOp]
29.             ReadMask[_StencilReadMask]
30.             WriteMask[_StencilWriteMask]
31.         }
32.  
33.             Blend SrcAlpha OneMinusSrcAlpha
34.             Cull Off
35.             Lighting Off
36.             ZWrite Off
37.             ColorMask[_ColorMask]
38.         Pass
39.         {
40.             CGPROGRAM
41.             #pragma vertex vert
42.             #pragma fragment frag
43.             // make fog work
44.             #pragma multi_compile_fog
45.            
46.             #include "UnityCG.cginc"
47.  
48.             struct appdata
49.             {
50.                 float4 vertex : POSITION;
51.                 float4 color    : COLOR;
52.                 float2 uv : TEXCOORD0;
53.             };
54.  
55.             struct v2f
56.             {
57.                 float2 uv : TEXCOORD0;
58.                 float2 uvTwo : TEXCOORD1;
59.                 fixed4 color : COLOR;
60.                 float4 vertex : SV_POSITION;
61.             };
62.  
63.             sampler2D _MainTex;
64.             sampler2D _LineTex;
65.             float4 _MainTex_ST;
66.             float4 _LineTex_ST;
67.             fixed4 _Color;
68.             fixed4 _FullLineColor;
69.            
70.             v2f vert (appdata v)
71.             {
72.                 v2f o;
73.                 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
74.                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
75.                 o.color = v.color * _Color;
76.                 o.uvTwo = TRANSFORM_TEX(v.uv, _LineTex);
77.                 return o;
78.             }
79.  
80.             fixed4 SampleSpriteTexture(float2 uv)
81.             {
82.                 fixed4 color = tex2D(_MainTex, uv);
83.  
84.                 return color;
85.             }
86.            
87.             fixed4 frag (v2f i) : SV_Target
88.             {
89.                 fixed4 col = SampleSpriteTexture(i.uv) * i.color;
90.  
91.                 col.rgb *= col.a;
92.  
93.                 fixed4 textureCol = (col.a * tex2D(_LineTex, i.uvTwo));
94.  
95.                 col.rgb = lerp(_Color, _FullLineColor, textureCol.a) * col.a;
96.  
97.                 return col;
98.             }
99.             ENDCG
100.         }
101.     }
102. }
103.  

Thanks