I've used Kenda tubes (not Kendra) for a few years and haven't had any problems.
Are you opening (unscrewing) the stem before you try to pump up the tube (tire)?
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.