Translation App - Runtime Error

I’m developing translation app these days. There is a list of pronunciation of words in native language is written in English letters and original native letter. operation of the app is basically when pronunciation of a word in native language is written in English letters in text box, combination of the English letters are find in the list and print in a label. Usually each word contains multiple combinations of English letter. Here are the blocks.

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I changed some variable values but got Runtime error every time. Please help me to fix this issue.