SSIS package fails to execute when run as a job

I'm trying to build a SSIS package in sql server to run an Excel import for me to a certain table when I follow all the steps using an import wizard and the import runs just fine. I save it as a file and try to run it again by double clicking it - it runs fine again. And yet when i setup a job in sql agent i get the following error:

> Message Executed as user: myusername Microsoft (R) SQL Server Execute
> Package Utility  Version 14.0.3025.39 for 32-bit  Copyright (C) 2017
> Microsoft. All rights reserved.    Started:  8:52:02 AM  Error:
> 2019-04-12 08:52:02.33     Code: 0xC0202009     Source: packagename
> Connection manager "SourceConnectionExcel"     Description: SSIS Error
> Code DTS_E_OLEDBERROR.  An OLE DB error has occurred. Error code:
> 0x80004005.  An OLE DB record is available.  Source: "Microsoft Access
> Database Engine"  Hresult: 0x80004005  Description: "Unspecified
> error".  End Error  Error: 2019-04-12 08:52:02.33     Code: 0xC020801C
> Source: Data Flow Task 1 Source - Query [29]     Description: SSIS
> Error Code DTS_E_CANNOTACQUIRECONNECTIONFROMCONNECTIONMANAGER.  The
> AcquireConnection method call to the connection manager
> "SourceConnectionExcel" failed with error code 0xC0202009.  There may
> be error messages posted before this with more information on why the
> AcquireConnection method call failed.  End Error  Error: 2019-04-12
> 08:52:02.33     Code: 0xC0047017     Source: Data Flow Task 1
> SSIS.Pipeline     Description: Source - Query failed validation and
> returned error code 0xC020801C.  End Error  Error: 2019-04-12
> 08:52:02.33     Code: 0xC004700C     Source: Data Flow Task 1
> SSIS.Pipeline     Description: One or more component failed
> validation.  End Error  Error: 2019-04-12 08:52:02.33     Code:
> 0xC0024107     Source: Data Flow Task 1      Description: There were
> errors during task validation.  End Error  DTExec: The package
> execution returned DTSER_FAILURE (1).  Started:  8:52:02 AM  Finished:
> 8:52:02 AM  Elapsed:  0.297 seconds.  The package execution failed. 
> The step failed.

What i did - I've configured the Credentials for my user and created a proxy user with also my credentials, which are able to access all necessary files and tables. Am I missing something? I've also tried to run it in 32 Bit mode - but no luck: ,