trouble installing OpenWRT build

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Describe the issue

When trying to install the package unum_2019.2.0_arm_cortex-a9_vfpv3.ipk on my wrt1900ac (not wrt1900acs), I get the following error... Any ideas as to why? This is on 18.06.2.

BusyBox v1.28.4 () built-in shell (ash)

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OpenWrt 18.06.2, r7676-cddd7b4c77

root@LEDE:~# opkg install ./unum_2019.2.0_arm_cortex-a9_vfpv3.ipk
Collected errors:

• pkg_init_from_file: Malformed package file ./unum_2019.2.0_arm_cortex-a9_vfpv3.ipk.
  root@LEDE:~# packet_write_wait: Connection to 192.168.2.1 port 22: Broken pipe