Continous Networking After Introduction

Hi,

i have the following problem.

I managed to connect to various people from in person events or by reaching out through LinkedIn. After an initial networking call, they often tell me they are currently looking for a position, that is not advertised and to send them my CV, or that they would love to introduce me to the wider team.

Now about half of the times, after I followed up on their offer and either sent them my resume or asked to be introduced to their team member, they end up ignoring me. I am super helpless and wanted to ask for your help.

Are they just to busy, I have sometimes even followed up after 2-3 weeks, but havent heard back from them. I also believe that they may only have been friendly, but were not really interested in me in the first place, but why would they offer, without me even asking to connect me or to send my resume over?

Thanks